Adding upstream version 115.8.0esr.upstream/115.8.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

17 files changed, 0 insertions, 5927 deletions

diff --git a/third_party/python/PyYAML/lib3/yaml/__init__.py b/third_party/python/PyYAML/lib3/yaml/__init__.py
deleted file mode 100644
index 86d07b5525..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/__init__.py
+++ /dev/null
@@ -1,427 +0,0 @@
-
-from .error import *
-
-from .tokens import *
-from .events import *
-from .nodes import *
-
-from .loader import *
-from .dumper import *
-
-__version__ = '5.4.1'
-try:
-    from .cyaml import *
-    __with_libyaml__ = True
-except ImportError:
-    __with_libyaml__ = False
-
-import io
-
-#------------------------------------------------------------------------------
-# Warnings control
-#------------------------------------------------------------------------------
-
-# 'Global' warnings state:
-_warnings_enabled = {
-    'YAMLLoadWarning': True,
-}
-
-# Get or set global warnings' state
-def warnings(settings=None):
-    if settings is None:
-        return _warnings_enabled
-
-    if type(settings) is dict:
-        for key in settings:
-            if key in _warnings_enabled:
-                _warnings_enabled[key] = settings[key]
-
-# Warn when load() is called without Loader=...
-class YAMLLoadWarning(RuntimeWarning):
-    pass
-
-def load_warning(method):
-    if _warnings_enabled['YAMLLoadWarning'] is False:
-        return
-
-    import warnings
-
-    message = (
-        "calling yaml.%s() without Loader=... is deprecated, as the "
-        "default Loader is unsafe. Please read "
-        "https://msg.pyyaml.org/load for full details."
-    ) % method
-
-    warnings.warn(message, YAMLLoadWarning, stacklevel=3)
-
-#------------------------------------------------------------------------------
-def scan(stream, Loader=Loader):
-    """
-    Scan a YAML stream and produce scanning tokens.
-    """
-    loader = Loader(stream)
-    try:
-        while loader.check_token():
-            yield loader.get_token()
-    finally:
-        loader.dispose()
-
-def parse(stream, Loader=Loader):
-    """
-    Parse a YAML stream and produce parsing events.
-    """
-    loader = Loader(stream)
-    try:
-        while loader.check_event():
-            yield loader.get_event()
-    finally:
-        loader.dispose()
-
-def compose(stream, Loader=Loader):
-    """
-    Parse the first YAML document in a stream
-    and produce the corresponding representation tree.
-    """
-    loader = Loader(stream)
-    try:
-        return loader.get_single_node()
-    finally:
-        loader.dispose()
-
-def compose_all(stream, Loader=Loader):
-    """
-    Parse all YAML documents in a stream
-    and produce corresponding representation trees.
-    """
-    loader = Loader(stream)
-    try:
-        while loader.check_node():
-            yield loader.get_node()
-    finally:
-        loader.dispose()
-
-def load(stream, Loader=None):
-    """
-    Parse the first YAML document in a stream
-    and produce the corresponding Python object.
-    """
-    if Loader is None:
-        load_warning('load')
-        Loader = FullLoader
-
-    loader = Loader(stream)
-    try:
-        return loader.get_single_data()
-    finally:
-        loader.dispose()
-
-def load_all(stream, Loader=None):
-    """
-    Parse all YAML documents in a stream
-    and produce corresponding Python objects.
-    """
-    if Loader is None:
-        load_warning('load_all')
-        Loader = FullLoader
-
-    loader = Loader(stream)
-    try:
-        while loader.check_data():
-            yield loader.get_data()
-    finally:
-        loader.dispose()
-
-def full_load(stream):
-    """
-    Parse the first YAML document in a stream
-    and produce the corresponding Python object.
-
-    Resolve all tags except those known to be
-    unsafe on untrusted input.
-    """
-    return load(stream, FullLoader)
-
-def full_load_all(stream):
-    """
-    Parse all YAML documents in a stream
-    and produce corresponding Python objects.
-
-    Resolve all tags except those known to be
-    unsafe on untrusted input.
-    """
-    return load_all(stream, FullLoader)
-
-def safe_load(stream):
-    """
-    Parse the first YAML document in a stream
-    and produce the corresponding Python object.
-
-    Resolve only basic YAML tags. This is known
-    to be safe for untrusted input.
-    """
-    return load(stream, SafeLoader)
-
-def safe_load_all(stream):
-    """
-    Parse all YAML documents in a stream
-    and produce corresponding Python objects.
-
-    Resolve only basic YAML tags. This is known
-    to be safe for untrusted input.
-    """
-    return load_all(stream, SafeLoader)
-
-def unsafe_load(stream):
-    """
-    Parse the first YAML document in a stream
-    and produce the corresponding Python object.
-
-    Resolve all tags, even those known to be
-    unsafe on untrusted input.
-    """
-    return load(stream, UnsafeLoader)
-
-def unsafe_load_all(stream):
-    """
-    Parse all YAML documents in a stream
-    and produce corresponding Python objects.
-
-    Resolve all tags, even those known to be
-    unsafe on untrusted input.
-    """
-    return load_all(stream, UnsafeLoader)
-
-def emit(events, stream=None, Dumper=Dumper,
-        canonical=None, indent=None, width=None,
-        allow_unicode=None, line_break=None):
-    """
-    Emit YAML parsing events into a stream.
-    If stream is None, return the produced string instead.
-    """
-    getvalue = None
-    if stream is None:
-        stream = io.StringIO()
-        getvalue = stream.getvalue
-    dumper = Dumper(stream, canonical=canonical, indent=indent, width=width,
-            allow_unicode=allow_unicode, line_break=line_break)
-    try:
-        for event in events:
-            dumper.emit(event)
-    finally:
-        dumper.dispose()
-    if getvalue:
-        return getvalue()
-
-def serialize_all(nodes, stream=None, Dumper=Dumper,
-        canonical=None, indent=None, width=None,
-        allow_unicode=None, line_break=None,
-        encoding=None, explicit_start=None, explicit_end=None,
-        version=None, tags=None):
-    """
-    Serialize a sequence of representation trees into a YAML stream.
-    If stream is None, return the produced string instead.
-    """
-    getvalue = None
-    if stream is None:
-        if encoding is None:
-            stream = io.StringIO()
-        else:
-            stream = io.BytesIO()
-        getvalue = stream.getvalue
-    dumper = Dumper(stream, canonical=canonical, indent=indent, width=width,
-            allow_unicode=allow_unicode, line_break=line_break,
-            encoding=encoding, version=version, tags=tags,
-            explicit_start=explicit_start, explicit_end=explicit_end)
-    try:
-        dumper.open()
-        for node in nodes:
-            dumper.serialize(node)
-        dumper.close()
-    finally:
-        dumper.dispose()
-    if getvalue:
-        return getvalue()
-
-def serialize(node, stream=None, Dumper=Dumper, **kwds):
-    """
-    Serialize a representation tree into a YAML stream.
-    If stream is None, return the produced string instead.
-    """
-    return serialize_all([node], stream, Dumper=Dumper, **kwds)
-
-def dump_all(documents, stream=None, Dumper=Dumper,
-        default_style=None, default_flow_style=False,
-        canonical=None, indent=None, width=None,
-        allow_unicode=None, line_break=None,
-        encoding=None, explicit_start=None, explicit_end=None,
-        version=None, tags=None, sort_keys=True):
-    """
-    Serialize a sequence of Python objects into a YAML stream.
-    If stream is None, return the produced string instead.
-    """
-    getvalue = None
-    if stream is None:
-        if encoding is None:
-            stream = io.StringIO()
-        else:
-            stream = io.BytesIO()
-        getvalue = stream.getvalue
-    dumper = Dumper(stream, default_style=default_style,
-            default_flow_style=default_flow_style,
-            canonical=canonical, indent=indent, width=width,
-            allow_unicode=allow_unicode, line_break=line_break,
-            encoding=encoding, version=version, tags=tags,
-            explicit_start=explicit_start, explicit_end=explicit_end, sort_keys=sort_keys)
-    try:
-        dumper.open()
-        for data in documents:
-            dumper.represent(data)
-        dumper.close()
-    finally:
-        dumper.dispose()
-    if getvalue:
-        return getvalue()
-
-def dump(data, stream=None, Dumper=Dumper, **kwds):
-    """
-    Serialize a Python object into a YAML stream.
-    If stream is None, return the produced string instead.
-    """
-    return dump_all([data], stream, Dumper=Dumper, **kwds)
-
-def safe_dump_all(documents, stream=None, **kwds):
-    """
-    Serialize a sequence of Python objects into a YAML stream.
-    Produce only basic YAML tags.
-    If stream is None, return the produced string instead.
-    """
-    return dump_all(documents, stream, Dumper=SafeDumper, **kwds)
-
-def safe_dump(data, stream=None, **kwds):
-    """
-    Serialize a Python object into a YAML stream.
-    Produce only basic YAML tags.
-    If stream is None, return the produced string instead.
-    """
-    return dump_all([data], stream, Dumper=SafeDumper, **kwds)
-
-def add_implicit_resolver(tag, regexp, first=None,
-        Loader=None, Dumper=Dumper):
-    """
-    Add an implicit scalar detector.
-    If an implicit scalar value matches the given regexp,
-    the corresponding tag is assigned to the scalar.
-    first is a sequence of possible initial characters or None.
-    """
-    if Loader is None:
-        loader.Loader.add_implicit_resolver(tag, regexp, first)
-        loader.FullLoader.add_implicit_resolver(tag, regexp, first)
-        loader.UnsafeLoader.add_implicit_resolver(tag, regexp, first)
-    else:
-        Loader.add_implicit_resolver(tag, regexp, first)
-    Dumper.add_implicit_resolver(tag, regexp, first)
-
-def add_path_resolver(tag, path, kind=None, Loader=None, Dumper=Dumper):
-    """
-    Add a path based resolver for the given tag.
-    A path is a list of keys that forms a path
-    to a node in the representation tree.
-    Keys can be string values, integers, or None.
-    """
-    if Loader is None:
-        loader.Loader.add_path_resolver(tag, path, kind)
-        loader.FullLoader.add_path_resolver(tag, path, kind)
-        loader.UnsafeLoader.add_path_resolver(tag, path, kind)
-    else:
-        Loader.add_path_resolver(tag, path, kind)
-    Dumper.add_path_resolver(tag, path, kind)
-
-def add_constructor(tag, constructor, Loader=None):
-    """
-    Add a constructor for the given tag.
-    Constructor is a function that accepts a Loader instance
-    and a node object and produces the corresponding Python object.
-    """
-    if Loader is None:
-        loader.Loader.add_constructor(tag, constructor)
-        loader.FullLoader.add_constructor(tag, constructor)
-        loader.UnsafeLoader.add_constructor(tag, constructor)
-    else:
-        Loader.add_constructor(tag, constructor)
-
-def add_multi_constructor(tag_prefix, multi_constructor, Loader=None):
-    """
-    Add a multi-constructor for the given tag prefix.
-    Multi-constructor is called for a node if its tag starts with tag_prefix.
-    Multi-constructor accepts a Loader instance, a tag suffix,
-    and a node object and produces the corresponding Python object.
-    """
-    if Loader is None:
-        loader.Loader.add_multi_constructor(tag_prefix, multi_constructor)
-        loader.FullLoader.add_multi_constructor(tag_prefix, multi_constructor)
-        loader.UnsafeLoader.add_multi_constructor(tag_prefix, multi_constructor)
-    else:
-        Loader.add_multi_constructor(tag_prefix, multi_constructor)
-
-def add_representer(data_type, representer, Dumper=Dumper):
-    """
-    Add a representer for the given type.
-    Representer is a function accepting a Dumper instance
-    and an instance of the given data type
-    and producing the corresponding representation node.
-    """
-    Dumper.add_representer(data_type, representer)
-
-def add_multi_representer(data_type, multi_representer, Dumper=Dumper):
-    """
-    Add a representer for the given type.
-    Multi-representer is a function accepting a Dumper instance
-    and an instance of the given data type or subtype
-    and producing the corresponding representation node.
-    """
-    Dumper.add_multi_representer(data_type, multi_representer)
-
-class YAMLObjectMetaclass(type):
-    """
-    The metaclass for YAMLObject.
-    """
-    def __init__(cls, name, bases, kwds):
-        super(YAMLObjectMetaclass, cls).__init__(name, bases, kwds)
-        if 'yaml_tag' in kwds and kwds['yaml_tag'] is not None:
-            if isinstance(cls.yaml_loader, list):
-                for loader in cls.yaml_loader:
-                    loader.add_constructor(cls.yaml_tag, cls.from_yaml)
-            else:
-                cls.yaml_loader.add_constructor(cls.yaml_tag, cls.from_yaml)
-
-            cls.yaml_dumper.add_representer(cls, cls.to_yaml)
-
-class YAMLObject(metaclass=YAMLObjectMetaclass):
-    """
-    An object that can dump itself to a YAML stream
-    and load itself from a YAML stream.
-    """
-
-    __slots__ = ()  # no direct instantiation, so allow immutable subclasses
-
-    yaml_loader = [Loader, FullLoader, UnsafeLoader]
-    yaml_dumper = Dumper
-
-    yaml_tag = None
-    yaml_flow_style = None
-
-    @classmethod
-    def from_yaml(cls, loader, node):
-        """
-        Convert a representation node to a Python object.
-        """
-        return loader.construct_yaml_object(node, cls)
-
-    @classmethod
-    def to_yaml(cls, dumper, data):
-        """
-        Convert a Python object to a representation node.
-        """
-        return dumper.represent_yaml_object(cls.yaml_tag, data, cls,
-                flow_style=cls.yaml_flow_style)
-
diff --git a/third_party/python/PyYAML/lib3/yaml/composer.py b/third_party/python/PyYAML/lib3/yaml/composer.py
deleted file mode 100644
index 6d15cb40e3..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/composer.py
+++ /dev/null
@@ -1,139 +0,0 @@
-
-__all__ = ['Composer', 'ComposerError']
-
-from .error import MarkedYAMLError
-from .events import *
-from .nodes import *
-
-class ComposerError(MarkedYAMLError):
-    pass
-
-class Composer:
-
-    def __init__(self):
-        self.anchors = {}
-
-    def check_node(self):
-        # Drop the STREAM-START event.
-        if self.check_event(StreamStartEvent):
-            self.get_event()
-
-        # If there are more documents available?
-        return not self.check_event(StreamEndEvent)
-
-    def get_node(self):
-        # Get the root node of the next document.
-        if not self.check_event(StreamEndEvent):
-            return self.compose_document()
-
-    def get_single_node(self):
-        # Drop the STREAM-START event.
-        self.get_event()
-
-        # Compose a document if the stream is not empty.
-        document = None
-        if not self.check_event(StreamEndEvent):
-            document = self.compose_document()
-
-        # Ensure that the stream contains no more documents.
-        if not self.check_event(StreamEndEvent):
-            event = self.get_event()
-            raise ComposerError("expected a single document in the stream",
-                    document.start_mark, "but found another document",
-                    event.start_mark)
-
-        # Drop the STREAM-END event.
-        self.get_event()
-
-        return document
-
-    def compose_document(self):
-        # Drop the DOCUMENT-START event.
-        self.get_event()
-
-        # Compose the root node.
-        node = self.compose_node(None, None)
-
-        # Drop the DOCUMENT-END event.
-        self.get_event()
-
-        self.anchors = {}
-        return node
-
-    def compose_node(self, parent, index):
-        if self.check_event(AliasEvent):
-            event = self.get_event()
-            anchor = event.anchor
-            if anchor not in self.anchors:
-                raise ComposerError(None, None, "found undefined alias %r"
-                        % anchor, event.start_mark)
-            return self.anchors[anchor]
-        event = self.peek_event()
-        anchor = event.anchor
-        if anchor is not None:
-            if anchor in self.anchors:
-                raise ComposerError("found duplicate anchor %r; first occurrence"
-                        % anchor, self.anchors[anchor].start_mark,
-                        "second occurrence", event.start_mark)
-        self.descend_resolver(parent, index)
-        if self.check_event(ScalarEvent):
-            node = self.compose_scalar_node(anchor)
-        elif self.check_event(SequenceStartEvent):
-            node = self.compose_sequence_node(anchor)
-        elif self.check_event(MappingStartEvent):
-            node = self.compose_mapping_node(anchor)
-        self.ascend_resolver()
-        return node
-
-    def compose_scalar_node(self, anchor):
-        event = self.get_event()
-        tag = event.tag
-        if tag is None or tag == '!':
-            tag = self.resolve(ScalarNode, event.value, event.implicit)
-        node = ScalarNode(tag, event.value,
-                event.start_mark, event.end_mark, style=event.style)
-        if anchor is not None:
-            self.anchors[anchor] = node
-        return node
-
-    def compose_sequence_node(self, anchor):
-        start_event = self.get_event()
-        tag = start_event.tag
-        if tag is None or tag == '!':
-            tag = self.resolve(SequenceNode, None, start_event.implicit)
-        node = SequenceNode(tag, [],
-                start_event.start_mark, None,
-                flow_style=start_event.flow_style)
-        if anchor is not None:
-            self.anchors[anchor] = node
-        index = 0
-        while not self.check_event(SequenceEndEvent):
-            node.value.append(self.compose_node(node, index))
-            index += 1
-        end_event = self.get_event()
-        node.end_mark = end_event.end_mark
-        return node
-
-    def compose_mapping_node(self, anchor):
-        start_event = self.get_event()
-        tag = start_event.tag
-        if tag is None or tag == '!':
-            tag = self.resolve(MappingNode, None, start_event.implicit)
-        node = MappingNode(tag, [],
-                start_event.start_mark, None,
-                flow_style=start_event.flow_style)
-        if anchor is not None:
-            self.anchors[anchor] = node
-        while not self.check_event(MappingEndEvent):
-            #key_event = self.peek_event()
-            item_key = self.compose_node(node, None)
-            #if item_key in node.value:
-            #    raise ComposerError("while composing a mapping", start_event.start_mark,
-            #            "found duplicate key", key_event.start_mark)
-            item_value = self.compose_node(node, item_key)
-            #node.value[item_key] = item_value
-            node.value.append((item_key, item_value))
-        end_event = self.get_event()
-        node.end_mark = end_event.end_mark
-        return node
-
diff --git a/third_party/python/PyYAML/lib3/yaml/constructor.py b/third_party/python/PyYAML/lib3/yaml/constructor.py
deleted file mode 100644
index 619acd3070..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/constructor.py
+++ /dev/null
@@ -1,748 +0,0 @@
-
-__all__ = [
-    'BaseConstructor',
-    'SafeConstructor',
-    'FullConstructor',
-    'UnsafeConstructor',
-    'Constructor',
-    'ConstructorError'
-]
-
-from .error import *
-from .nodes import *
-
-import collections.abc, datetime, base64, binascii, re, sys, types
-
-class ConstructorError(MarkedYAMLError):
-    pass
-
-class BaseConstructor:
-
-    yaml_constructors = {}
-    yaml_multi_constructors = {}
-
-    def __init__(self):
-        self.constructed_objects = {}
-        self.recursive_objects = {}
-        self.state_generators = []
-        self.deep_construct = False
-
-    def check_data(self):
-        # If there are more documents available?
-        return self.check_node()
-
-    def check_state_key(self, key):
-        """Block special attributes/methods from being set in a newly created
-        object, to prevent user-controlled methods from being called during
-        deserialization"""
-        if self.get_state_keys_blacklist_regexp().match(key):
-            raise ConstructorError(None, None,
-                "blacklisted key '%s' in instance state found" % (key,), None)
-
-    def get_data(self):
-        # Construct and return the next document.
-        if self.check_node():
-            return self.construct_document(self.get_node())
-
-    def get_single_data(self):
-        # Ensure that the stream contains a single document and construct it.
-        node = self.get_single_node()
-        if node is not None:
-            return self.construct_document(node)
-        return None
-
-    def construct_document(self, node):
-        data = self.construct_object(node)
-        while self.state_generators:
-            state_generators = self.state_generators
-            self.state_generators = []
-            for generator in state_generators:
-                for dummy in generator:
-                    pass
-        self.constructed_objects = {}
-        self.recursive_objects = {}
-        self.deep_construct = False
-        return data
-
-    def construct_object(self, node, deep=False):
-        if node in self.constructed_objects:
-            return self.constructed_objects[node]
-        if deep:
-            old_deep = self.deep_construct
-            self.deep_construct = True
-        if node in self.recursive_objects:
-            raise ConstructorError(None, None,
-                    "found unconstructable recursive node", node.start_mark)
-        self.recursive_objects[node] = None
-        constructor = None
-        tag_suffix = None
-        if node.tag in self.yaml_constructors:
-            constructor = self.yaml_constructors[node.tag]
-        else:
-            for tag_prefix in self.yaml_multi_constructors:
-                if tag_prefix is not None and node.tag.startswith(tag_prefix):
-                    tag_suffix = node.tag[len(tag_prefix):]
-                    constructor = self.yaml_multi_constructors[tag_prefix]
-                    break
-            else:
-                if None in self.yaml_multi_constructors:
-                    tag_suffix = node.tag
-                    constructor = self.yaml_multi_constructors[None]
-                elif None in self.yaml_constructors:
-                    constructor = self.yaml_constructors[None]
-                elif isinstance(node, ScalarNode):
-                    constructor = self.__class__.construct_scalar
-                elif isinstance(node, SequenceNode):
-                    constructor = self.__class__.construct_sequence
-                elif isinstance(node, MappingNode):
-                    constructor = self.__class__.construct_mapping
-        if tag_suffix is None:
-            data = constructor(self, node)
-        else:
-            data = constructor(self, tag_suffix, node)
-        if isinstance(data, types.GeneratorType):
-            generator = data
-            data = next(generator)
-            if self.deep_construct:
-                for dummy in generator:
-                    pass
-            else:
-                self.state_generators.append(generator)
-        self.constructed_objects[node] = data
-        del self.recursive_objects[node]
-        if deep:
-            self.deep_construct = old_deep
-        return data
-
-    def construct_scalar(self, node):
-        if not isinstance(node, ScalarNode):
-            raise ConstructorError(None, None,
-                    "expected a scalar node, but found %s" % node.id,
-                    node.start_mark)
-        return node.value
-
-    def construct_sequence(self, node, deep=False):
-        if not isinstance(node, SequenceNode):
-            raise ConstructorError(None, None,
-                    "expected a sequence node, but found %s" % node.id,
-                    node.start_mark)
-        return [self.construct_object(child, deep=deep)
-                for child in node.value]
-
-    def construct_mapping(self, node, deep=False):
-        if not isinstance(node, MappingNode):
-            raise ConstructorError(None, None,
-                    "expected a mapping node, but found %s" % node.id,
-                    node.start_mark)
-        mapping = {}
-        for key_node, value_node in node.value:
-            key = self.construct_object(key_node, deep=deep)
-            if not isinstance(key, collections.abc.Hashable):
-                raise ConstructorError("while constructing a mapping", node.start_mark,
-                        "found unhashable key", key_node.start_mark)
-            value = self.construct_object(value_node, deep=deep)
-            mapping[key] = value
-        return mapping
-
-    def construct_pairs(self, node, deep=False):
-        if not isinstance(node, MappingNode):
-            raise ConstructorError(None, None,
-                    "expected a mapping node, but found %s" % node.id,
-                    node.start_mark)
-        pairs = []
-        for key_node, value_node in node.value:
-            key = self.construct_object(key_node, deep=deep)
-            value = self.construct_object(value_node, deep=deep)
-            pairs.append((key, value))
-        return pairs
-
-    @classmethod
-    def add_constructor(cls, tag, constructor):
-        if not 'yaml_constructors' in cls.__dict__:
-            cls.yaml_constructors = cls.yaml_constructors.copy()
-        cls.yaml_constructors[tag] = constructor
-
-    @classmethod
-    def add_multi_constructor(cls, tag_prefix, multi_constructor):
-        if not 'yaml_multi_constructors' in cls.__dict__:
-            cls.yaml_multi_constructors = cls.yaml_multi_constructors.copy()
-        cls.yaml_multi_constructors[tag_prefix] = multi_constructor
-
-class SafeConstructor(BaseConstructor):
-
-    def construct_scalar(self, node):
-        if isinstance(node, MappingNode):
-            for key_node, value_node in node.value:
-                if key_node.tag == 'tag:yaml.org,2002:value':
-                    return self.construct_scalar(value_node)
-        return super().construct_scalar(node)
-
-    def flatten_mapping(self, node):
-        merge = []
-        index = 0
-        while index < len(node.value):
-            key_node, value_node = node.value[index]
-            if key_node.tag == 'tag:yaml.org,2002:merge':
-                del node.value[index]
-                if isinstance(value_node, MappingNode):
-                    self.flatten_mapping(value_node)
-                    merge.extend(value_node.value)
-                elif isinstance(value_node, SequenceNode):
-                    submerge = []
-                    for subnode in value_node.value:
-                        if not isinstance(subnode, MappingNode):
-                            raise ConstructorError("while constructing a mapping",
-                                    node.start_mark,
-                                    "expected a mapping for merging, but found %s"
-                                    % subnode.id, subnode.start_mark)
-                        self.flatten_mapping(subnode)
-                        submerge.append(subnode.value)
-                    submerge.reverse()
-                    for value in submerge:
-                        merge.extend(value)
-                else:
-                    raise ConstructorError("while constructing a mapping", node.start_mark,
-                            "expected a mapping or list of mappings for merging, but found %s"
-                            % value_node.id, value_node.start_mark)
-            elif key_node.tag == 'tag:yaml.org,2002:value':
-                key_node.tag = 'tag:yaml.org,2002:str'
-                index += 1
-            else:
-                index += 1
-        if merge:
-            node.value = merge + node.value
-
-    def construct_mapping(self, node, deep=False):
-        if isinstance(node, MappingNode):
-            self.flatten_mapping(node)
-        return super().construct_mapping(node, deep=deep)
-
-    def construct_yaml_null(self, node):
-        self.construct_scalar(node)
-        return None
-
-    bool_values = {
-        'yes':      True,
-        'no':       False,
-        'true':     True,
-        'false':    False,
-        'on':       True,
-        'off':      False,
-    }
-
-    def construct_yaml_bool(self, node):
-        value = self.construct_scalar(node)
-        return self.bool_values[value.lower()]
-
-    def construct_yaml_int(self, node):
-        value = self.construct_scalar(node)
-        value = value.replace('_', '')
-        sign = +1
-        if value[0] == '-':
-            sign = -1
-        if value[0] in '+-':
-            value = value[1:]
-        if value == '0':
-            return 0
-        elif value.startswith('0b'):
-            return sign*int(value[2:], 2)
-        elif value.startswith('0x'):
-            return sign*int(value[2:], 16)
-        elif value[0] == '0':
-            return sign*int(value, 8)
-        elif ':' in value:
-            digits = [int(part) for part in value.split(':')]
-            digits.reverse()
-            base = 1
-            value = 0
-            for digit in digits:
-                value += digit*base
-                base *= 60
-            return sign*value
-        else:
-            return sign*int(value)
-
-    inf_value = 1e300
-    while inf_value != inf_value*inf_value:
-        inf_value *= inf_value
-    nan_value = -inf_value/inf_value   # Trying to make a quiet NaN (like C99).
-
-    def construct_yaml_float(self, node):
-        value = self.construct_scalar(node)
-        value = value.replace('_', '').lower()
-        sign = +1
-        if value[0] == '-':
-            sign = -1
-        if value[0] in '+-':
-            value = value[1:]
-        if value == '.inf':
-            return sign*self.inf_value
-        elif value == '.nan':
-            return self.nan_value
-        elif ':' in value:
-            digits = [float(part) for part in value.split(':')]
-            digits.reverse()
-            base = 1
-            value = 0.0
-            for digit in digits:
-                value += digit*base
-                base *= 60
-            return sign*value
-        else:
-            return sign*float(value)
-
-    def construct_yaml_binary(self, node):
-        try:
-            value = self.construct_scalar(node).encode('ascii')
-        except UnicodeEncodeError as exc:
-            raise ConstructorError(None, None,
-                    "failed to convert base64 data into ascii: %s" % exc,
-                    node.start_mark)
-        try:
-            if hasattr(base64, 'decodebytes'):
-                return base64.decodebytes(value)
-            else:
-                return base64.decodestring(value)
-        except binascii.Error as exc:
-            raise ConstructorError(None, None,
-                    "failed to decode base64 data: %s" % exc, node.start_mark)
-
-    timestamp_regexp = re.compile(
-            r'''^(?P<year>[0-9][0-9][0-9][0-9])
-                -(?P<month>[0-9][0-9]?)
-                -(?P<day>[0-9][0-9]?)
-                (?:(?:[Tt]|[ \t]+)
-                (?P<hour>[0-9][0-9]?)
-                :(?P<minute>[0-9][0-9])
-                :(?P<second>[0-9][0-9])
-                (?:\.(?P<fraction>[0-9]*))?
-                (?:[ \t]*(?P<tz>Z|(?P<tz_sign>[-+])(?P<tz_hour>[0-9][0-9]?)
-                (?::(?P<tz_minute>[0-9][0-9]))?))?)?$''', re.X)
-
-    def construct_yaml_timestamp(self, node):
-        value = self.construct_scalar(node)
-        match = self.timestamp_regexp.match(node.value)
-        values = match.groupdict()
-        year = int(values['year'])
-        month = int(values['month'])
-        day = int(values['day'])
-        if not values['hour']:
-            return datetime.date(year, month, day)
-        hour = int(values['hour'])
-        minute = int(values['minute'])
-        second = int(values['second'])
-        fraction = 0
-        tzinfo = None
-        if values['fraction']:
-            fraction = values['fraction'][:6]
-            while len(fraction) < 6:
-                fraction += '0'
-            fraction = int(fraction)
-        if values['tz_sign']:
-            tz_hour = int(values['tz_hour'])
-            tz_minute = int(values['tz_minute'] or 0)
-            delta = datetime.timedelta(hours=tz_hour, minutes=tz_minute)
-            if values['tz_sign'] == '-':
-                delta = -delta
-            tzinfo = datetime.timezone(delta)
-        elif values['tz']:
-            tzinfo = datetime.timezone.utc
-        return datetime.datetime(year, month, day, hour, minute, second, fraction,
-                                 tzinfo=tzinfo)
-
-    def construct_yaml_omap(self, node):
-        # Note: we do not check for duplicate keys, because it's too
-        # CPU-expensive.
-        omap = []
-        yield omap
-        if not isinstance(node, SequenceNode):
-            raise ConstructorError("while constructing an ordered map", node.start_mark,
-                    "expected a sequence, but found %s" % node.id, node.start_mark)
-        for subnode in node.value:
-            if not isinstance(subnode, MappingNode):
-                raise ConstructorError("while constructing an ordered map", node.start_mark,
-                        "expected a mapping of length 1, but found %s" % subnode.id,
-                        subnode.start_mark)
-            if len(subnode.value) != 1:
-                raise ConstructorError("while constructing an ordered map", node.start_mark,
-                        "expected a single mapping item, but found %d items" % len(subnode.value),
-                        subnode.start_mark)
-            key_node, value_node = subnode.value[0]
-            key = self.construct_object(key_node)
-            value = self.construct_object(value_node)
-            omap.append((key, value))
-
-    def construct_yaml_pairs(self, node):
-        # Note: the same code as `construct_yaml_omap`.
-        pairs = []
-        yield pairs
-        if not isinstance(node, SequenceNode):
-            raise ConstructorError("while constructing pairs", node.start_mark,
-                    "expected a sequence, but found %s" % node.id, node.start_mark)
-        for subnode in node.value:
-            if not isinstance(subnode, MappingNode):
-                raise ConstructorError("while constructing pairs", node.start_mark,
-                        "expected a mapping of length 1, but found %s" % subnode.id,
-                        subnode.start_mark)
-            if len(subnode.value) != 1:
-                raise ConstructorError("while constructing pairs", node.start_mark,
-                        "expected a single mapping item, but found %d items" % len(subnode.value),
-                        subnode.start_mark)
-            key_node, value_node = subnode.value[0]
-            key = self.construct_object(key_node)
-            value = self.construct_object(value_node)
-            pairs.append((key, value))
-
-    def construct_yaml_set(self, node):
-        data = set()
-        yield data
-        value = self.construct_mapping(node)
-        data.update(value)
-
-    def construct_yaml_str(self, node):
-        return self.construct_scalar(node)
-
-    def construct_yaml_seq(self, node):
-        data = []
-        yield data
-        data.extend(self.construct_sequence(node))
-
-    def construct_yaml_map(self, node):
-        data = {}
-        yield data
-        value = self.construct_mapping(node)
-        data.update(value)
-
-    def construct_yaml_object(self, node, cls):
-        data = cls.__new__(cls)
-        yield data
-        if hasattr(data, '__setstate__'):
-            state = self.construct_mapping(node, deep=True)
-            data.__setstate__(state)
-        else:
-            state = self.construct_mapping(node)
-            data.__dict__.update(state)
-
-    def construct_undefined(self, node):
-        raise ConstructorError(None, None,
-                "could not determine a constructor for the tag %r" % node.tag,
-                node.start_mark)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:null',
-        SafeConstructor.construct_yaml_null)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:bool',
-        SafeConstructor.construct_yaml_bool)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:int',
-        SafeConstructor.construct_yaml_int)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:float',
-        SafeConstructor.construct_yaml_float)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:binary',
-        SafeConstructor.construct_yaml_binary)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:timestamp',
-        SafeConstructor.construct_yaml_timestamp)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:omap',
-        SafeConstructor.construct_yaml_omap)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:pairs',
-        SafeConstructor.construct_yaml_pairs)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:set',
-        SafeConstructor.construct_yaml_set)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:str',
-        SafeConstructor.construct_yaml_str)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:seq',
-        SafeConstructor.construct_yaml_seq)
-
-SafeConstructor.add_constructor(
-        'tag:yaml.org,2002:map',
-        SafeConstructor.construct_yaml_map)
-
-SafeConstructor.add_constructor(None,
-        SafeConstructor.construct_undefined)
-
-class FullConstructor(SafeConstructor):
-    # 'extend' is blacklisted because it is used by
-    # construct_python_object_apply to add `listitems` to a newly generate
-    # python instance
-    def get_state_keys_blacklist(self):
-        return ['^extend$', '^__.*__$']
-
-    def get_state_keys_blacklist_regexp(self):
-        if not hasattr(self, 'state_keys_blacklist_regexp'):
-            self.state_keys_blacklist_regexp = re.compile('(' + '|'.join(self.get_state_keys_blacklist()) + ')')
-        return self.state_keys_blacklist_regexp
-
-    def construct_python_str(self, node):
-        return self.construct_scalar(node)
-
-    def construct_python_unicode(self, node):
-        return self.construct_scalar(node)
-
-    def construct_python_bytes(self, node):
-        try:
-            value = self.construct_scalar(node).encode('ascii')
-        except UnicodeEncodeError as exc:
-            raise ConstructorError(None, None,
-                    "failed to convert base64 data into ascii: %s" % exc,
-                    node.start_mark)
-        try:
-            if hasattr(base64, 'decodebytes'):
-                return base64.decodebytes(value)
-            else:
-                return base64.decodestring(value)
-        except binascii.Error as exc:
-            raise ConstructorError(None, None,
-                    "failed to decode base64 data: %s" % exc, node.start_mark)
-
-    def construct_python_long(self, node):
-        return self.construct_yaml_int(node)
-
-    def construct_python_complex(self, node):
-       return complex(self.construct_scalar(node))
-
-    def construct_python_tuple(self, node):
-        return tuple(self.construct_sequence(node))
-
-    def find_python_module(self, name, mark, unsafe=False):
-        if not name:
-            raise ConstructorError("while constructing a Python module", mark,
-                    "expected non-empty name appended to the tag", mark)
-        if unsafe:
-            try:
-                __import__(name)
-            except ImportError as exc:
-                raise ConstructorError("while constructing a Python module", mark,
-                        "cannot find module %r (%s)" % (name, exc), mark)
-        if name not in sys.modules:
-            raise ConstructorError("while constructing a Python module", mark,
-                    "module %r is not imported" % name, mark)
-        return sys.modules[name]
-
-    def find_python_name(self, name, mark, unsafe=False):
-        if not name:
-            raise ConstructorError("while constructing a Python object", mark,
-                    "expected non-empty name appended to the tag", mark)
-        if '.' in name:
-            module_name, object_name = name.rsplit('.', 1)
-        else:
-            module_name = 'builtins'
-            object_name = name
-        if unsafe:
-            try:
-                __import__(module_name)
-            except ImportError as exc:
-                raise ConstructorError("while constructing a Python object", mark,
-                        "cannot find module %r (%s)" % (module_name, exc), mark)
-        if module_name not in sys.modules:
-            raise ConstructorError("while constructing a Python object", mark,
-                    "module %r is not imported" % module_name, mark)
-        module = sys.modules[module_name]
-        if not hasattr(module, object_name):
-            raise ConstructorError("while constructing a Python object", mark,
-                    "cannot find %r in the module %r"
-                    % (object_name, module.__name__), mark)
-        return getattr(module, object_name)
-
-    def construct_python_name(self, suffix, node):
-        value = self.construct_scalar(node)
-        if value:
-            raise ConstructorError("while constructing a Python name", node.start_mark,
-                    "expected the empty value, but found %r" % value, node.start_mark)
-        return self.find_python_name(suffix, node.start_mark)
-
-    def construct_python_module(self, suffix, node):
-        value = self.construct_scalar(node)
-        if value:
-            raise ConstructorError("while constructing a Python module", node.start_mark,
-                    "expected the empty value, but found %r" % value, node.start_mark)
-        return self.find_python_module(suffix, node.start_mark)
-
-    def make_python_instance(self, suffix, node,
-            args=None, kwds=None, newobj=False, unsafe=False):
-        if not args:
-            args = []
-        if not kwds:
-            kwds = {}
-        cls = self.find_python_name(suffix, node.start_mark)
-        if not (unsafe or isinstance(cls, type)):
-            raise ConstructorError("while constructing a Python instance", node.start_mark,
-                    "expected a class, but found %r" % type(cls),
-                    node.start_mark)
-        if newobj and isinstance(cls, type):
-            return cls.__new__(cls, *args, **kwds)
-        else:
-            return cls(*args, **kwds)
-
-    def set_python_instance_state(self, instance, state, unsafe=False):
-        if hasattr(instance, '__setstate__'):
-            instance.__setstate__(state)
-        else:
-            slotstate = {}
-            if isinstance(state, tuple) and len(state) == 2:
-                state, slotstate = state
-            if hasattr(instance, '__dict__'):
-                if not unsafe and state:
-                    for key in state.keys():
-                        self.check_state_key(key)
-                instance.__dict__.update(state)
-            elif state:
-                slotstate.update(state)
-            for key, value in slotstate.items():
-                if not unsafe:
-                    self.check_state_key(key)
-                setattr(instance, key, value)
-
-    def construct_python_object(self, suffix, node):
-        # Format:
-        #   !!python/object:module.name { ... state ... }
-        instance = self.make_python_instance(suffix, node, newobj=True)
-        yield instance
-        deep = hasattr(instance, '__setstate__')
-        state = self.construct_mapping(node, deep=deep)
-        self.set_python_instance_state(instance, state)
-
-    def construct_python_object_apply(self, suffix, node, newobj=False):
-        # Format:
-        #   !!python/object/apply       # (or !!python/object/new)
-        #   args: [ ... arguments ... ]
-        #   kwds: { ... keywords ... }
-        #   state: ... state ...
-        #   listitems: [ ... listitems ... ]
-        #   dictitems: { ... dictitems ... }
-        # or short format:
-        #   !!python/object/apply [ ... arguments ... ]
-        # The difference between !!python/object/apply and !!python/object/new
-        # is how an object is created, check make_python_instance for details.
-        if isinstance(node, SequenceNode):
-            args = self.construct_sequence(node, deep=True)
-            kwds = {}
-            state = {}
-            listitems = []
-            dictitems = {}
-        else:
-            value = self.construct_mapping(node, deep=True)
-            args = value.get('args', [])
-            kwds = value.get('kwds', {})
-            state = value.get('state', {})
-            listitems = value.get('listitems', [])
-            dictitems = value.get('dictitems', {})
-        instance = self.make_python_instance(suffix, node, args, kwds, newobj)
-        if state:
-            self.set_python_instance_state(instance, state)
-        if listitems:
-            instance.extend(listitems)
-        if dictitems:
-            for key in dictitems:
-                instance[key] = dictitems[key]
-        return instance
-
-    def construct_python_object_new(self, suffix, node):
-        return self.construct_python_object_apply(suffix, node, newobj=True)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/none',
-    FullConstructor.construct_yaml_null)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/bool',
-    FullConstructor.construct_yaml_bool)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/str',
-    FullConstructor.construct_python_str)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/unicode',
-    FullConstructor.construct_python_unicode)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/bytes',
-    FullConstructor.construct_python_bytes)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/int',
-    FullConstructor.construct_yaml_int)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/long',
-    FullConstructor.construct_python_long)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/float',
-    FullConstructor.construct_yaml_float)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/complex',
-    FullConstructor.construct_python_complex)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/list',
-    FullConstructor.construct_yaml_seq)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/tuple',
-    FullConstructor.construct_python_tuple)
-
-FullConstructor.add_constructor(
-    'tag:yaml.org,2002:python/dict',
-    FullConstructor.construct_yaml_map)
-
-FullConstructor.add_multi_constructor(
-    'tag:yaml.org,2002:python/name:',
-    FullConstructor.construct_python_name)
-
-class UnsafeConstructor(FullConstructor):
-
-    def find_python_module(self, name, mark):
-        return super(UnsafeConstructor, self).find_python_module(name, mark, unsafe=True)
-
-    def find_python_name(self, name, mark):
-        return super(UnsafeConstructor, self).find_python_name(name, mark, unsafe=True)
-
-    def make_python_instance(self, suffix, node, args=None, kwds=None, newobj=False):
-        return super(UnsafeConstructor, self).make_python_instance(
-            suffix, node, args, kwds, newobj, unsafe=True)
-
-    def set_python_instance_state(self, instance, state):
-        return super(UnsafeConstructor, self).set_python_instance_state(
-            instance, state, unsafe=True)
-
-UnsafeConstructor.add_multi_constructor(
-    'tag:yaml.org,2002:python/module:',
-    UnsafeConstructor.construct_python_module)
-
-UnsafeConstructor.add_multi_constructor(
-    'tag:yaml.org,2002:python/object:',
-    UnsafeConstructor.construct_python_object)
-
-UnsafeConstructor.add_multi_constructor(
-    'tag:yaml.org,2002:python/object/new:',
-    UnsafeConstructor.construct_python_object_new)
-
-UnsafeConstructor.add_multi_constructor(
-    'tag:yaml.org,2002:python/object/apply:',
-    UnsafeConstructor.construct_python_object_apply)
-
-# Constructor is same as UnsafeConstructor. Need to leave this in place in case
-# people have extended it directly.
-class Constructor(UnsafeConstructor):
-    pass
diff --git a/third_party/python/PyYAML/lib3/yaml/cyaml.py b/third_party/python/PyYAML/lib3/yaml/cyaml.py
deleted file mode 100644
index 0c21345879..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/cyaml.py
+++ /dev/null
@@ -1,101 +0,0 @@
-
-__all__ = [
-    'CBaseLoader', 'CSafeLoader', 'CFullLoader', 'CUnsafeLoader', 'CLoader',
-    'CBaseDumper', 'CSafeDumper', 'CDumper'
-]
-
-from yaml._yaml import CParser, CEmitter
-
-from .constructor import *
-
-from .serializer import *
-from .representer import *
-
-from .resolver import *
-
-class CBaseLoader(CParser, BaseConstructor, BaseResolver):
-
-    def __init__(self, stream):
-        CParser.__init__(self, stream)
-        BaseConstructor.__init__(self)
-        BaseResolver.__init__(self)
-
-class CSafeLoader(CParser, SafeConstructor, Resolver):
-
-    def __init__(self, stream):
-        CParser.__init__(self, stream)
-        SafeConstructor.__init__(self)
-        Resolver.__init__(self)
-
-class CFullLoader(CParser, FullConstructor, Resolver):
-
-    def __init__(self, stream):
-        CParser.__init__(self, stream)
-        FullConstructor.__init__(self)
-        Resolver.__init__(self)
-
-class CUnsafeLoader(CParser, UnsafeConstructor, Resolver):
-
-    def __init__(self, stream):
-        CParser.__init__(self, stream)
-        UnsafeConstructor.__init__(self)
-        Resolver.__init__(self)
-
-class CLoader(CParser, Constructor, Resolver):
-
-    def __init__(self, stream):
-        CParser.__init__(self, stream)
-        Constructor.__init__(self)
-        Resolver.__init__(self)
-
-class CBaseDumper(CEmitter, BaseRepresenter, BaseResolver):
-
-    def __init__(self, stream,
-            default_style=None, default_flow_style=False,
-            canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None,
-            encoding=None, explicit_start=None, explicit_end=None,
-            version=None, tags=None, sort_keys=True):
-        CEmitter.__init__(self, stream, canonical=canonical,
-                indent=indent, width=width, encoding=encoding,
-                allow_unicode=allow_unicode, line_break=line_break,
-                explicit_start=explicit_start, explicit_end=explicit_end,
-                version=version, tags=tags)
-        Representer.__init__(self, default_style=default_style,
-                default_flow_style=default_flow_style, sort_keys=sort_keys)
-        Resolver.__init__(self)
-
-class CSafeDumper(CEmitter, SafeRepresenter, Resolver):
-
-    def __init__(self, stream,
-            default_style=None, default_flow_style=False,
-            canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None,
-            encoding=None, explicit_start=None, explicit_end=None,
-            version=None, tags=None, sort_keys=True):
-        CEmitter.__init__(self, stream, canonical=canonical,
-                indent=indent, width=width, encoding=encoding,
-                allow_unicode=allow_unicode, line_break=line_break,
-                explicit_start=explicit_start, explicit_end=explicit_end,
-                version=version, tags=tags)
-        SafeRepresenter.__init__(self, default_style=default_style,
-                default_flow_style=default_flow_style, sort_keys=sort_keys)
-        Resolver.__init__(self)
-
-class CDumper(CEmitter, Serializer, Representer, Resolver):
-
-    def __init__(self, stream,
-            default_style=None, default_flow_style=False,
-            canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None,
-            encoding=None, explicit_start=None, explicit_end=None,
-            version=None, tags=None, sort_keys=True):
-        CEmitter.__init__(self, stream, canonical=canonical,
-                indent=indent, width=width, encoding=encoding,
-                allow_unicode=allow_unicode, line_break=line_break,
-                explicit_start=explicit_start, explicit_end=explicit_end,
-                version=version, tags=tags)
-        Representer.__init__(self, default_style=default_style,
-                default_flow_style=default_flow_style, sort_keys=sort_keys)
-        Resolver.__init__(self)
-
diff --git a/third_party/python/PyYAML/lib3/yaml/dumper.py b/third_party/python/PyYAML/lib3/yaml/dumper.py
deleted file mode 100644
index 6aadba551f..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/dumper.py
+++ /dev/null
@@ -1,62 +0,0 @@
-
-__all__ = ['BaseDumper', 'SafeDumper', 'Dumper']
-
-from .emitter import *
-from .serializer import *
-from .representer import *
-from .resolver import *
-
-class BaseDumper(Emitter, Serializer, BaseRepresenter, BaseResolver):
-
-    def __init__(self, stream,
-            default_style=None, default_flow_style=False,
-            canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None,
-            encoding=None, explicit_start=None, explicit_end=None,
-            version=None, tags=None, sort_keys=True):
-        Emitter.__init__(self, stream, canonical=canonical,
-                indent=indent, width=width,
-                allow_unicode=allow_unicode, line_break=line_break)
-        Serializer.__init__(self, encoding=encoding,
-                explicit_start=explicit_start, explicit_end=explicit_end,
-                version=version, tags=tags)
-        Representer.__init__(self, default_style=default_style,
-                default_flow_style=default_flow_style, sort_keys=sort_keys)
-        Resolver.__init__(self)
-
-class SafeDumper(Emitter, Serializer, SafeRepresenter, Resolver):
-
-    def __init__(self, stream,
-            default_style=None, default_flow_style=False,
-            canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None,
-            encoding=None, explicit_start=None, explicit_end=None,
-            version=None, tags=None, sort_keys=True):
-        Emitter.__init__(self, stream, canonical=canonical,
-                indent=indent, width=width,
-                allow_unicode=allow_unicode, line_break=line_break)
-        Serializer.__init__(self, encoding=encoding,
-                explicit_start=explicit_start, explicit_end=explicit_end,
-                version=version, tags=tags)
-        SafeRepresenter.__init__(self, default_style=default_style,
-                default_flow_style=default_flow_style, sort_keys=sort_keys)
-        Resolver.__init__(self)
-
-class Dumper(Emitter, Serializer, Representer, Resolver):
-
-    def __init__(self, stream,
-            default_style=None, default_flow_style=False,
-            canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None,
-            encoding=None, explicit_start=None, explicit_end=None,
-            version=None, tags=None, sort_keys=True):
-        Emitter.__init__(self, stream, canonical=canonical,
-                indent=indent, width=width,
-                allow_unicode=allow_unicode, line_break=line_break)
-        Serializer.__init__(self, encoding=encoding,
-                explicit_start=explicit_start, explicit_end=explicit_end,
-                version=version, tags=tags)
-        Representer.__init__(self, default_style=default_style,
-                default_flow_style=default_flow_style, sort_keys=sort_keys)
-        Resolver.__init__(self)
-
diff --git a/third_party/python/PyYAML/lib3/yaml/emitter.py b/third_party/python/PyYAML/lib3/yaml/emitter.py
deleted file mode 100644
index a664d01116..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/emitter.py
+++ /dev/null
@@ -1,1137 +0,0 @@
-
-# Emitter expects events obeying the following grammar:
-# stream ::= STREAM-START document* STREAM-END
-# document ::= DOCUMENT-START node DOCUMENT-END
-# node ::= SCALAR | sequence | mapping
-# sequence ::= SEQUENCE-START node* SEQUENCE-END
-# mapping ::= MAPPING-START (node node)* MAPPING-END
-
-__all__ = ['Emitter', 'EmitterError']
-
-from .error import YAMLError
-from .events import *
-
-class EmitterError(YAMLError):
-    pass
-
-class ScalarAnalysis:
-    def __init__(self, scalar, empty, multiline,
-            allow_flow_plain, allow_block_plain,
-            allow_single_quoted, allow_double_quoted,
-            allow_block):
-        self.scalar = scalar
-        self.empty = empty
-        self.multiline = multiline
-        self.allow_flow_plain = allow_flow_plain
-        self.allow_block_plain = allow_block_plain
-        self.allow_single_quoted = allow_single_quoted
-        self.allow_double_quoted = allow_double_quoted
-        self.allow_block = allow_block
-
-class Emitter:
-
-    DEFAULT_TAG_PREFIXES = {
-        '!' : '!',
-        'tag:yaml.org,2002:' : '!!',
-    }
-
-    def __init__(self, stream, canonical=None, indent=None, width=None,
-            allow_unicode=None, line_break=None):
-
-        # The stream should have the methods `write` and possibly `flush`.
-        self.stream = stream
-
-        # Encoding can be overridden by STREAM-START.
-        self.encoding = None
-
-        # Emitter is a state machine with a stack of states to handle nested
-        # structures.
-        self.states = []
-        self.state = self.expect_stream_start
-
-        # Current event and the event queue.
-        self.events = []
-        self.event = None
-
-        # The current indentation level and the stack of previous indents.
-        self.indents = []
-        self.indent = None
-
-        # Flow level.
-        self.flow_level = 0
-
-        # Contexts.
-        self.root_context = False
-        self.sequence_context = False
-        self.mapping_context = False
-        self.simple_key_context = False
-
-        # Characteristics of the last emitted character:
-        #  - current position.
-        #  - is it a whitespace?
-        #  - is it an indention character
-        #    (indentation space, '-', '?', or ':')?
-        self.line = 0
-        self.column = 0
-        self.whitespace = True
-        self.indention = True
-
-        # Whether the document requires an explicit document indicator
-        self.open_ended = False
-
-        # Formatting details.
-        self.canonical = canonical
-        self.allow_unicode = allow_unicode
-        self.best_indent = 2
-        if indent and 1 < indent < 10:
-            self.best_indent = indent
-        self.best_width = 80
-        if width and width > self.best_indent*2:
-            self.best_width = width
-        self.best_line_break = '\n'
-        if line_break in ['\r', '\n', '\r\n']:
-            self.best_line_break = line_break
-
-        # Tag prefixes.
-        self.tag_prefixes = None
-
-        # Prepared anchor and tag.
-        self.prepared_anchor = None
-        self.prepared_tag = None
-
-        # Scalar analysis and style.
-        self.analysis = None
-        self.style = None
-
-    def dispose(self):
-        # Reset the state attributes (to clear self-references)
-        self.states = []
-        self.state = None
-
-    def emit(self, event):
-        self.events.append(event)
-        while not self.need_more_events():
-            self.event = self.events.pop(0)
-            self.state()
-            self.event = None
-
-    # In some cases, we wait for a few next events before emitting.
-
-    def need_more_events(self):
-        if not self.events:
-            return True
-        event = self.events[0]
-        if isinstance(event, DocumentStartEvent):
-            return self.need_events(1)
-        elif isinstance(event, SequenceStartEvent):
-            return self.need_events(2)
-        elif isinstance(event, MappingStartEvent):
-            return self.need_events(3)
-        else:
-            return False
-
-    def need_events(self, count):
-        level = 0
-        for event in self.events[1:]:
-            if isinstance(event, (DocumentStartEvent, CollectionStartEvent)):
-                level += 1
-            elif isinstance(event, (DocumentEndEvent, CollectionEndEvent)):
-                level -= 1
-            elif isinstance(event, StreamEndEvent):
-                level = -1
-            if level < 0:
-                return False
-        return (len(self.events) < count+1)
-
-    def increase_indent(self, flow=False, indentless=False):
-        self.indents.append(self.indent)
-        if self.indent is None:
-            if flow:
-                self.indent = self.best_indent
-            else:
-                self.indent = 0
-        elif not indentless:
-            self.indent += self.best_indent
-
-    # States.
-
-    # Stream handlers.
-
-    def expect_stream_start(self):
-        if isinstance(self.event, StreamStartEvent):
-            if self.event.encoding and not hasattr(self.stream, 'encoding'):
-                self.encoding = self.event.encoding
-            self.write_stream_start()
-            self.state = self.expect_first_document_start
-        else:
-            raise EmitterError("expected StreamStartEvent, but got %s"
-                    % self.event)
-
-    def expect_nothing(self):
-        raise EmitterError("expected nothing, but got %s" % self.event)
-
-    # Document handlers.
-
-    def expect_first_document_start(self):
-        return self.expect_document_start(first=True)
-
-    def expect_document_start(self, first=False):
-        if isinstance(self.event, DocumentStartEvent):
-            if (self.event.version or self.event.tags) and self.open_ended:
-                self.write_indicator('...', True)
-                self.write_indent()
-            if self.event.version:
-                version_text = self.prepare_version(self.event.version)
-                self.write_version_directive(version_text)
-            self.tag_prefixes = self.DEFAULT_TAG_PREFIXES.copy()
-            if self.event.tags:
-                handles = sorted(self.event.tags.keys())
-                for handle in handles:
-                    prefix = self.event.tags[handle]
-                    self.tag_prefixes[prefix] = handle
-                    handle_text = self.prepare_tag_handle(handle)
-                    prefix_text = self.prepare_tag_prefix(prefix)
-                    self.write_tag_directive(handle_text, prefix_text)
-            implicit = (first and not self.event.explicit and not self.canonical
-                    and not self.event.version and not self.event.tags
-                    and not self.check_empty_document())
-            if not implicit:
-                self.write_indent()
-                self.write_indicator('---', True)
-                if self.canonical:
-                    self.write_indent()
-            self.state = self.expect_document_root
-        elif isinstance(self.event, StreamEndEvent):
-            if self.open_ended:
-                self.write_indicator('...', True)
-                self.write_indent()
-            self.write_stream_end()
-            self.state = self.expect_nothing
-        else:
-            raise EmitterError("expected DocumentStartEvent, but got %s"
-                    % self.event)
-
-    def expect_document_end(self):
-        if isinstance(self.event, DocumentEndEvent):
-            self.write_indent()
-            if self.event.explicit:
-                self.write_indicator('...', True)
-                self.write_indent()
-            self.flush_stream()
-            self.state = self.expect_document_start
-        else:
-            raise EmitterError("expected DocumentEndEvent, but got %s"
-                    % self.event)
-
-    def expect_document_root(self):
-        self.states.append(self.expect_document_end)
-        self.expect_node(root=True)
-
-    # Node handlers.
-
-    def expect_node(self, root=False, sequence=False, mapping=False,
-            simple_key=False):
-        self.root_context = root
-        self.sequence_context = sequence
-        self.mapping_context = mapping
-        self.simple_key_context = simple_key
-        if isinstance(self.event, AliasEvent):
-            self.expect_alias()
-        elif isinstance(self.event, (ScalarEvent, CollectionStartEvent)):
-            self.process_anchor('&')
-            self.process_tag()
-            if isinstance(self.event, ScalarEvent):
-                self.expect_scalar()
-            elif isinstance(self.event, SequenceStartEvent):
-                if self.flow_level or self.canonical or self.event.flow_style   \
-                        or self.check_empty_sequence():
-                    self.expect_flow_sequence()
-                else:
-                    self.expect_block_sequence()
-            elif isinstance(self.event, MappingStartEvent):
-                if self.flow_level or self.canonical or self.event.flow_style   \
-                        or self.check_empty_mapping():
-                    self.expect_flow_mapping()
-                else:
-                    self.expect_block_mapping()
-        else:
-            raise EmitterError("expected NodeEvent, but got %s" % self.event)
-
-    def expect_alias(self):
-        if self.event.anchor is None:
-            raise EmitterError("anchor is not specified for alias")
-        self.process_anchor('*')
-        self.state = self.states.pop()
-
-    def expect_scalar(self):
-        self.increase_indent(flow=True)
-        self.process_scalar()
-        self.indent = self.indents.pop()
-        self.state = self.states.pop()
-
-    # Flow sequence handlers.
-
-    def expect_flow_sequence(self):
-        self.write_indicator('[', True, whitespace=True)
-        self.flow_level += 1
-        self.increase_indent(flow=True)
-        self.state = self.expect_first_flow_sequence_item
-
-    def expect_first_flow_sequence_item(self):
-        if isinstance(self.event, SequenceEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            self.write_indicator(']', False)
-            self.state = self.states.pop()
-        else:
-            if self.canonical or self.column > self.best_width:
-                self.write_indent()
-            self.states.append(self.expect_flow_sequence_item)
-            self.expect_node(sequence=True)
-
-    def expect_flow_sequence_item(self):
-        if isinstance(self.event, SequenceEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            if self.canonical:
-                self.write_indicator(',', False)
-                self.write_indent()
-            self.write_indicator(']', False)
-            self.state = self.states.pop()
-        else:
-            self.write_indicator(',', False)
-            if self.canonical or self.column > self.best_width:
-                self.write_indent()
-            self.states.append(self.expect_flow_sequence_item)
-            self.expect_node(sequence=True)
-
-    # Flow mapping handlers.
-
-    def expect_flow_mapping(self):
-        self.write_indicator('{', True, whitespace=True)
-        self.flow_level += 1
-        self.increase_indent(flow=True)
-        self.state = self.expect_first_flow_mapping_key
-
-    def expect_first_flow_mapping_key(self):
-        if isinstance(self.event, MappingEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            self.write_indicator('}', False)
-            self.state = self.states.pop()
-        else:
-            if self.canonical or self.column > self.best_width:
-                self.write_indent()
-            if not self.canonical and self.check_simple_key():
-                self.states.append(self.expect_flow_mapping_simple_value)
-                self.expect_node(mapping=True, simple_key=True)
-            else:
-                self.write_indicator('?', True)
-                self.states.append(self.expect_flow_mapping_value)
-                self.expect_node(mapping=True)
-
-    def expect_flow_mapping_key(self):
-        if isinstance(self.event, MappingEndEvent):
-            self.indent = self.indents.pop()
-            self.flow_level -= 1
-            if self.canonical:
-                self.write_indicator(',', False)
-                self.write_indent()
-            self.write_indicator('}', False)
-            self.state = self.states.pop()
-        else:
-            self.write_indicator(',', False)
-            if self.canonical or self.column > self.best_width:
-                self.write_indent()
-            if not self.canonical and self.check_simple_key():
-                self.states.append(self.expect_flow_mapping_simple_value)
-                self.expect_node(mapping=True, simple_key=True)
-            else:
-                self.write_indicator('?', True)
-                self.states.append(self.expect_flow_mapping_value)
-                self.expect_node(mapping=True)
-
-    def expect_flow_mapping_simple_value(self):
-        self.write_indicator(':', False)
-        self.states.append(self.expect_flow_mapping_key)
-        self.expect_node(mapping=True)
-
-    def expect_flow_mapping_value(self):
-        if self.canonical or self.column > self.best_width:
-            self.write_indent()
-        self.write_indicator(':', True)
-        self.states.append(self.expect_flow_mapping_key)
-        self.expect_node(mapping=True)
-
-    # Block sequence handlers.
-
-    def expect_block_sequence(self):
-        indentless = (self.mapping_context and not self.indention)
-        self.increase_indent(flow=False, indentless=indentless)
-        self.state = self.expect_first_block_sequence_item
-
-    def expect_first_block_sequence_item(self):
-        return self.expect_block_sequence_item(first=True)
-
-    def expect_block_sequence_item(self, first=False):
-        if not first and isinstance(self.event, SequenceEndEvent):
-            self.indent = self.indents.pop()
-            self.state = self.states.pop()
-        else:
-            self.write_indent()
-            self.write_indicator('-', True, indention=True)
-            self.states.append(self.expect_block_sequence_item)
-            self.expect_node(sequence=True)
-
-    # Block mapping handlers.
-
-    def expect_block_mapping(self):
-        self.increase_indent(flow=False)
-        self.state = self.expect_first_block_mapping_key
-
-    def expect_first_block_mapping_key(self):
-        return self.expect_block_mapping_key(first=True)
-
-    def expect_block_mapping_key(self, first=False):
-        if not first and isinstance(self.event, MappingEndEvent):
-            self.indent = self.indents.pop()
-            self.state = self.states.pop()
-        else:
-            self.write_indent()
-            if self.check_simple_key():
-                self.states.append(self.expect_block_mapping_simple_value)
-                self.expect_node(mapping=True, simple_key=True)
-            else:
-                self.write_indicator('?', True, indention=True)
-                self.states.append(self.expect_block_mapping_value)
-                self.expect_node(mapping=True)
-
-    def expect_block_mapping_simple_value(self):
-        self.write_indicator(':', False)
-        self.states.append(self.expect_block_mapping_key)
-        self.expect_node(mapping=True)
-
-    def expect_block_mapping_value(self):
-        self.write_indent()
-        self.write_indicator(':', True, indention=True)
-        self.states.append(self.expect_block_mapping_key)
-        self.expect_node(mapping=True)
-
-    # Checkers.
-
-    def check_empty_sequence(self):
-        return (isinstance(self.event, SequenceStartEvent) and self.events
-                and isinstance(self.events[0], SequenceEndEvent))
-
-    def check_empty_mapping(self):
-        return (isinstance(self.event, MappingStartEvent) and self.events
-                and isinstance(self.events[0], MappingEndEvent))
-
-    def check_empty_document(self):
-        if not isinstance(self.event, DocumentStartEvent) or not self.events:
-            return False
-        event = self.events[0]
-        return (isinstance(event, ScalarEvent) and event.anchor is None
-                and event.tag is None and event.implicit and event.value == '')
-
-    def check_simple_key(self):
-        length = 0
-        if isinstance(self.event, NodeEvent) and self.event.anchor is not None:
-            if self.prepared_anchor is None:
-                self.prepared_anchor = self.prepare_anchor(self.event.anchor)
-            length += len(self.prepared_anchor)
-        if isinstance(self.event, (ScalarEvent, CollectionStartEvent))  \
-                and self.event.tag is not None:
-            if self.prepared_tag is None:
-                self.prepared_tag = self.prepare_tag(self.event.tag)
-            length += len(self.prepared_tag)
-        if isinstance(self.event, ScalarEvent):
-            if self.analysis is None:
-                self.analysis = self.analyze_scalar(self.event.value)
-            length += len(self.analysis.scalar)
-        return (length < 128 and (isinstance(self.event, AliasEvent)
-            or (isinstance(self.event, ScalarEvent)
-                    and not self.analysis.empty and not self.analysis.multiline)
-            or self.check_empty_sequence() or self.check_empty_mapping()))
-
-    # Anchor, Tag, and Scalar processors.
-
-    def process_anchor(self, indicator):
-        if self.event.anchor is None:
-            self.prepared_anchor = None
-            return
-        if self.prepared_anchor is None:
-            self.prepared_anchor = self.prepare_anchor(self.event.anchor)
-        if self.prepared_anchor:
-            self.write_indicator(indicator+self.prepared_anchor, True)
-        self.prepared_anchor = None
-
-    def process_tag(self):
-        tag = self.event.tag
-        if isinstance(self.event, ScalarEvent):
-            if self.style is None:
-                self.style = self.choose_scalar_style()
-            if ((not self.canonical or tag is None) and
-                ((self.style == '' and self.event.implicit[0])
-                        or (self.style != '' and self.event.implicit[1]))):
-                self.prepared_tag = None
-                return
-            if self.event.implicit[0] and tag is None:
-                tag = '!'
-                self.prepared_tag = None
-        else:
-            if (not self.canonical or tag is None) and self.event.implicit:
-                self.prepared_tag = None
-                return
-        if tag is None:
-            raise EmitterError("tag is not specified")
-        if self.prepared_tag is None:
-            self.prepared_tag = self.prepare_tag(tag)
-        if self.prepared_tag:
-            self.write_indicator(self.prepared_tag, True)
-        self.prepared_tag = None
-
-    def choose_scalar_style(self):
-        if self.analysis is None:
-            self.analysis = self.analyze_scalar(self.event.value)
-        if self.event.style == '"' or self.canonical:
-            return '"'
-        if not self.event.style and self.event.implicit[0]:
-            if (not (self.simple_key_context and
-                    (self.analysis.empty or self.analysis.multiline))
-                and (self.flow_level and self.analysis.allow_flow_plain
-                    or (not self.flow_level and self.analysis.allow_block_plain))):
-                return ''
-        if self.event.style and self.event.style in '|>':
-            if (not self.flow_level and not self.simple_key_context
-                    and self.analysis.allow_block):
-                return self.event.style
-        if not self.event.style or self.event.style == '\'':
-            if (self.analysis.allow_single_quoted and
-                    not (self.simple_key_context and self.analysis.multiline)):
-                return '\''
-        return '"'
-
-    def process_scalar(self):
-        if self.analysis is None:
-            self.analysis = self.analyze_scalar(self.event.value)
-        if self.style is None:
-            self.style = self.choose_scalar_style()
-        split = (not self.simple_key_context)
-        #if self.analysis.multiline and split    \
-        #        and (not self.style or self.style in '\'\"'):
-        #    self.write_indent()
-        if self.style == '"':
-            self.write_double_quoted(self.analysis.scalar, split)
-        elif self.style == '\'':
-            self.write_single_quoted(self.analysis.scalar, split)
-        elif self.style == '>':
-            self.write_folded(self.analysis.scalar)
-        elif self.style == '|':
-            self.write_literal(self.analysis.scalar)
-        else:
-            self.write_plain(self.analysis.scalar, split)
-        self.analysis = None
-        self.style = None
-
-    # Analyzers.
-
-    def prepare_version(self, version):
-        major, minor = version
-        if major != 1:
-            raise EmitterError("unsupported YAML version: %d.%d" % (major, minor))
-        return '%d.%d' % (major, minor)
-
-    def prepare_tag_handle(self, handle):
-        if not handle:
-            raise EmitterError("tag handle must not be empty")
-        if handle[0] != '!' or handle[-1] != '!':
-            raise EmitterError("tag handle must start and end with '!': %r" % handle)
-        for ch in handle[1:-1]:
-            if not ('0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'    \
-                    or ch in '-_'):
-                raise EmitterError("invalid character %r in the tag handle: %r"
-                        % (ch, handle))
-        return handle
-
-    def prepare_tag_prefix(self, prefix):
-        if not prefix:
-            raise EmitterError("tag prefix must not be empty")
-        chunks = []
-        start = end = 0
-        if prefix[0] == '!':
-            end = 1
-        while end < len(prefix):
-            ch = prefix[end]
-            if '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
-                    or ch in '-;/?!:@&=+$,_.~*\'()[]':
-                end += 1
-            else:
-                if start < end:
-                    chunks.append(prefix[start:end])
-                start = end = end+1
-                data = ch.encode('utf-8')
-                for ch in data:
-                    chunks.append('%%%02X' % ord(ch))
-        if start < end:
-            chunks.append(prefix[start:end])
-        return ''.join(chunks)
-
-    def prepare_tag(self, tag):
-        if not tag:
-            raise EmitterError("tag must not be empty")
-        if tag == '!':
-            return tag
-        handle = None
-        suffix = tag
-        prefixes = sorted(self.tag_prefixes.keys())
-        for prefix in prefixes:
-            if tag.startswith(prefix)   \
-                    and (prefix == '!' or len(prefix) < len(tag)):
-                handle = self.tag_prefixes[prefix]
-                suffix = tag[len(prefix):]
-        chunks = []
-        start = end = 0
-        while end < len(suffix):
-            ch = suffix[end]
-            if '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z' \
-                    or ch in '-;/?:@&=+$,_.~*\'()[]'   \
-                    or (ch == '!' and handle != '!'):
-                end += 1
-            else:
-                if start < end:
-                    chunks.append(suffix[start:end])
-                start = end = end+1
-                data = ch.encode('utf-8')
-                for ch in data:
-                    chunks.append('%%%02X' % ch)
-        if start < end:
-            chunks.append(suffix[start:end])
-        suffix_text = ''.join(chunks)
-        if handle:
-            return '%s%s' % (handle, suffix_text)
-        else:
-            return '!<%s>' % suffix_text
-
-    def prepare_anchor(self, anchor):
-        if not anchor:
-            raise EmitterError("anchor must not be empty")
-        for ch in anchor:
-            if not ('0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'    \
-                    or ch in '-_'):
-                raise EmitterError("invalid character %r in the anchor: %r"
-                        % (ch, anchor))
-        return anchor
-
-    def analyze_scalar(self, scalar):
-
-        # Empty scalar is a special case.
-        if not scalar:
-            return ScalarAnalysis(scalar=scalar, empty=True, multiline=False,
-                    allow_flow_plain=False, allow_block_plain=True,
-                    allow_single_quoted=True, allow_double_quoted=True,
-                    allow_block=False)
-
-        # Indicators and special characters.
-        block_indicators = False
-        flow_indicators = False
-        line_breaks = False
-        special_characters = False
-
-        # Important whitespace combinations.
-        leading_space = False
-        leading_break = False
-        trailing_space = False
-        trailing_break = False
-        break_space = False
-        space_break = False
-
-        # Check document indicators.
-        if scalar.startswith('---') or scalar.startswith('...'):
-            block_indicators = True
-            flow_indicators = True
-
-        # First character or preceded by a whitespace.
-        preceded_by_whitespace = True
-
-        # Last character or followed by a whitespace.
-        followed_by_whitespace = (len(scalar) == 1 or
-                scalar[1] in '\0 \t\r\n\x85\u2028\u2029')
-
-        # The previous character is a space.
-        previous_space = False
-
-        # The previous character is a break.
-        previous_break = False
-
-        index = 0
-        while index < len(scalar):
-            ch = scalar[index]
-
-            # Check for indicators.
-            if index == 0:
-                # Leading indicators are special characters.
-                if ch in '#,[]{}&*!|>\'\"%@`':
-                    flow_indicators = True
-                    block_indicators = True
-                if ch in '?:':
-                    flow_indicators = True
-                    if followed_by_whitespace:
-                        block_indicators = True
-                if ch == '-' and followed_by_whitespace:
-                    flow_indicators = True
-                    block_indicators = True
-            else:
-                # Some indicators cannot appear within a scalar as well.
-                if ch in ',?[]{}':
-                    flow_indicators = True
-                if ch == ':':
-                    flow_indicators = True
-                    if followed_by_whitespace:
-                        block_indicators = True
-                if ch == '#' and preceded_by_whitespace:
-                    flow_indicators = True
-                    block_indicators = True
-
-            # Check for line breaks, special, and unicode characters.
-            if ch in '\n\x85\u2028\u2029':
-                line_breaks = True
-            if not (ch == '\n' or '\x20' <= ch <= '\x7E'):
-                if (ch == '\x85' or '\xA0' <= ch <= '\uD7FF'
-                        or '\uE000' <= ch <= '\uFFFD'
-                        or '\U00010000' <= ch < '\U0010ffff') and ch != '\uFEFF':
-                    unicode_characters = True
-                    if not self.allow_unicode:
-                        special_characters = True
-                else:
-                    special_characters = True
-
-            # Detect important whitespace combinations.
-            if ch == ' ':
-                if index == 0:
-                    leading_space = True
-                if index == len(scalar)-1:
-                    trailing_space = True
-                if previous_break:
-                    break_space = True
-                previous_space = True
-                previous_break = False
-            elif ch in '\n\x85\u2028\u2029':
-                if index == 0:
-                    leading_break = True
-                if index == len(scalar)-1:
-                    trailing_break = True
-                if previous_space:
-                    space_break = True
-                previous_space = False
-                previous_break = True
-            else:
-                previous_space = False
-                previous_break = False
-
-            # Prepare for the next character.
-            index += 1
-            preceded_by_whitespace = (ch in '\0 \t\r\n\x85\u2028\u2029')
-            followed_by_whitespace = (index+1 >= len(scalar) or
-                    scalar[index+1] in '\0 \t\r\n\x85\u2028\u2029')
-
-        # Let's decide what styles are allowed.
-        allow_flow_plain = True
-        allow_block_plain = True
-        allow_single_quoted = True
-        allow_double_quoted = True
-        allow_block = True
-
-        # Leading and trailing whitespaces are bad for plain scalars.
-        if (leading_space or leading_break
-                or trailing_space or trailing_break):
-            allow_flow_plain = allow_block_plain = False
-
-        # We do not permit trailing spaces for block scalars.
-        if trailing_space:
-            allow_block = False
-
-        # Spaces at the beginning of a new line are only acceptable for block
-        # scalars.
-        if break_space:
-            allow_flow_plain = allow_block_plain = allow_single_quoted = False
-
-        # Spaces followed by breaks, as well as special character are only
-        # allowed for double quoted scalars.
-        if space_break or special_characters:
-            allow_flow_plain = allow_block_plain =  \
-            allow_single_quoted = allow_block = False
-
-        # Although the plain scalar writer supports breaks, we never emit
-        # multiline plain scalars.
-        if line_breaks:
-            allow_flow_plain = allow_block_plain = False
-
-        # Flow indicators are forbidden for flow plain scalars.
-        if flow_indicators:
-            allow_flow_plain = False
-
-        # Block indicators are forbidden for block plain scalars.
-        if block_indicators:
-            allow_block_plain = False
-
-        return ScalarAnalysis(scalar=scalar,
-                empty=False, multiline=line_breaks,
-                allow_flow_plain=allow_flow_plain,
-                allow_block_plain=allow_block_plain,
-                allow_single_quoted=allow_single_quoted,
-                allow_double_quoted=allow_double_quoted,
-                allow_block=allow_block)
-
-    # Writers.
-
-    def flush_stream(self):
-        if hasattr(self.stream, 'flush'):
-            self.stream.flush()
-
-    def write_stream_start(self):
-        # Write BOM if needed.
-        if self.encoding and self.encoding.startswith('utf-16'):
-            self.stream.write('\uFEFF'.encode(self.encoding))
-
-    def write_stream_end(self):
-        self.flush_stream()
-
-    def write_indicator(self, indicator, need_whitespace,
-            whitespace=False, indention=False):
-        if self.whitespace or not need_whitespace:
-            data = indicator
-        else:
-            data = ' '+indicator
-        self.whitespace = whitespace
-        self.indention = self.indention and indention
-        self.column += len(data)
-        self.open_ended = False
-        if self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-
-    def write_indent(self):
-        indent = self.indent or 0
-        if not self.indention or self.column > indent   \
-                or (self.column == indent and not self.whitespace):
-            self.write_line_break()
-        if self.column < indent:
-            self.whitespace = True
-            data = ' '*(indent-self.column)
-            self.column = indent
-            if self.encoding:
-                data = data.encode(self.encoding)
-            self.stream.write(data)
-
-    def write_line_break(self, data=None):
-        if data is None:
-            data = self.best_line_break
-        self.whitespace = True
-        self.indention = True
-        self.line += 1
-        self.column = 0
-        if self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-
-    def write_version_directive(self, version_text):
-        data = '%%YAML %s' % version_text
-        if self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-        self.write_line_break()
-
-    def write_tag_directive(self, handle_text, prefix_text):
-        data = '%%TAG %s %s' % (handle_text, prefix_text)
-        if self.encoding:
-            data = data.encode(self.encoding)
-        self.stream.write(data)
-        self.write_line_break()
-
-    # Scalar streams.
-
-    def write_single_quoted(self, text, split=True):
-        self.write_indicator('\'', True)
-        spaces = False
-        breaks = False
-        start = end = 0
-        while end <= len(text):
-            ch = None
-            if end < len(text):
-                ch = text[end]
-            if spaces:
-                if ch is None or ch != ' ':
-                    if start+1 == end and self.column > self.best_width and split   \
-                            and start != 0 and end != len(text):
-                        self.write_indent()
-                    else:
-                        data = text[start:end]
-                        self.column += len(data)
-                        if self.encoding:
-                            data = data.encode(self.encoding)
-                        self.stream.write(data)
-                    start = end
-            elif breaks:
-                if ch is None or ch not in '\n\x85\u2028\u2029':
-                    if text[start] == '\n':
-                        self.write_line_break()
-                    for br in text[start:end]:
-                        if br == '\n':
-                            self.write_line_break()
-                        else:
-                            self.write_line_break(br)
-                    self.write_indent()
-                    start = end
-            else:
-                if ch is None or ch in ' \n\x85\u2028\u2029' or ch == '\'':
-                    if start < end:
-                        data = text[start:end]
-                        self.column += len(data)
-                        if self.encoding:
-                            data = data.encode(self.encoding)
-                        self.stream.write(data)
-                        start = end
-            if ch == '\'':
-                data = '\'\''
-                self.column += 2
-                if self.encoding:
-                    data = data.encode(self.encoding)
-                self.stream.write(data)
-                start = end + 1
-            if ch is not None:
-                spaces = (ch == ' ')
-                breaks = (ch in '\n\x85\u2028\u2029')
-            end += 1
-        self.write_indicator('\'', False)
-
-    ESCAPE_REPLACEMENTS = {
-        '\0':       '0',
-        '\x07':     'a',
-        '\x08':     'b',
-        '\x09':     't',
-        '\x0A':     'n',
-        '\x0B':     'v',
-        '\x0C':     'f',
-        '\x0D':     'r',
-        '\x1B':     'e',
-        '\"':       '\"',
-        '\\':       '\\',
-        '\x85':     'N',
-        '\xA0':     '_',
-        '\u2028':   'L',
-        '\u2029':   'P',
-    }
-
-    def write_double_quoted(self, text, split=True):
-        self.write_indicator('"', True)
-        start = end = 0
-        while end <= len(text):
-            ch = None
-            if end < len(text):
-                ch = text[end]
-            if ch is None or ch in '"\\\x85\u2028\u2029\uFEFF' \
-                    or not ('\x20' <= ch <= '\x7E'
-                        or (self.allow_unicode
-                            and ('\xA0' <= ch <= '\uD7FF'
-                                or '\uE000' <= ch <= '\uFFFD'))):
-                if start < end:
-                    data = text[start:end]
-                    self.column += len(data)
-                    if self.encoding:
-                        data = data.encode(self.encoding)
-                    self.stream.write(data)
-                    start = end
-                if ch is not None:
-                    if ch in self.ESCAPE_REPLACEMENTS:
-                        data = '\\'+self.ESCAPE_REPLACEMENTS[ch]
-                    elif ch <= '\xFF':
-                        data = '\\x%02X' % ord(ch)
-                    elif ch <= '\uFFFF':
-                        data = '\\u%04X' % ord(ch)
-                    else:
-                        data = '\\U%08X' % ord(ch)
-                    self.column += len(data)
-                    if self.encoding:
-                        data = data.encode(self.encoding)
-                    self.stream.write(data)
-                    start = end+1
-            if 0 < end < len(text)-1 and (ch == ' ' or start >= end)    \
-                    and self.column+(end-start) > self.best_width and split:
-                data = text[start:end]+'\\'
-                if start < end:
-                    start = end
-                self.column += len(data)
-                if self.encoding:
-                    data = data.encode(self.encoding)
-                self.stream.write(data)
-                self.write_indent()
-                self.whitespace = False
-                self.indention = False
-                if text[start] == ' ':
-                    data = '\\'
-                    self.column += len(data)
-                    if self.encoding:
-                        data = data.encode(self.encoding)
-                    self.stream.write(data)
-            end += 1
-        self.write_indicator('"', False)
-
-    def determine_block_hints(self, text):
-        hints = ''
-        if text:
-            if text[0] in ' \n\x85\u2028\u2029':
-                hints += str(self.best_indent)
-            if text[-1] not in '\n\x85\u2028\u2029':
-                hints += '-'
-            elif len(text) == 1 or text[-2] in '\n\x85\u2028\u2029':
-                hints += '+'
-        return hints
-
-    def write_folded(self, text):
-        hints = self.determine_block_hints(text)
-        self.write_indicator('>'+hints, True)
-        if hints[-1:] == '+':
-            self.open_ended = True
-        self.write_line_break()
-        leading_space = True
-        spaces = False
-        breaks = True
-        start = end = 0
-        while end <= len(text):
-            ch = None
-            if end < len(text):
-                ch = text[end]
-            if breaks:
-                if ch is None or ch not in '\n\x85\u2028\u2029':
-                    if not leading_space and ch is not None and ch != ' '   \
-                            and text[start] == '\n':
-                        self.write_line_break()
-                    leading_space = (ch == ' ')
-                    for br in text[start:end]:
-                        if br == '\n':
-                            self.write_line_break()
-                        else:
-                            self.write_line_break(br)
-                    if ch is not None:
-                        self.write_indent()
-                    start = end
-            elif spaces:
-                if ch != ' ':
-                    if start+1 == end and self.column > self.best_width:
-                        self.write_indent()
-                    else:
-                        data = text[start:end]
-                        self.column += len(data)
-                        if self.encoding:
-                            data = data.encode(self.encoding)
-                        self.stream.write(data)
-                    start = end
-            else:
-                if ch is None or ch in ' \n\x85\u2028\u2029':
-                    data = text[start:end]
-                    self.column += len(data)
-                    if self.encoding:
-                        data = data.encode(self.encoding)
-                    self.stream.write(data)
-                    if ch is None:
-                        self.write_line_break()
-                    start = end
-            if ch is not None:
-                breaks = (ch in '\n\x85\u2028\u2029')
-                spaces = (ch == ' ')
-            end += 1
-
-    def write_literal(self, text):
-        hints = self.determine_block_hints(text)
-        self.write_indicator('|'+hints, True)
-        if hints[-1:] == '+':
-            self.open_ended = True
-        self.write_line_break()
-        breaks = True
-        start = end = 0
-        while end <= len(text):
-            ch = None
-            if end < len(text):
-                ch = text[end]
-            if breaks:
-                if ch is None or ch not in '\n\x85\u2028\u2029':
-                    for br in text[start:end]:
-                        if br == '\n':
-                            self.write_line_break()
-                        else:
-                            self.write_line_break(br)
-                    if ch is not None:
-                        self.write_indent()
-                    start = end
-            else:
-                if ch is None or ch in '\n\x85\u2028\u2029':
-                    data = text[start:end]
-                    if self.encoding:
-                        data = data.encode(self.encoding)
-                    self.stream.write(data)
-                    if ch is None:
-                        self.write_line_break()
-                    start = end
-            if ch is not None:
-                breaks = (ch in '\n\x85\u2028\u2029')
-            end += 1
-
-    def write_plain(self, text, split=True):
-        if self.root_context:
-            self.open_ended = True
-        if not text:
-            return
-        if not self.whitespace:
-            data = ' '
-            self.column += len(data)
-            if self.encoding:
-                data = data.encode(self.encoding)
-            self.stream.write(data)
-        self.whitespace = False
-        self.indention = False
-        spaces = False
-        breaks = False
-        start = end = 0
-        while end <= len(text):
-            ch = None
-            if end < len(text):
-                ch = text[end]
-            if spaces:
-                if ch != ' ':
-                    if start+1 == end and self.column > self.best_width and split:
-                        self.write_indent()
-                        self.whitespace = False
-                        self.indention = False
-                    else:
-                        data = text[start:end]
-                        self.column += len(data)
-                        if self.encoding:
-                            data = data.encode(self.encoding)
-                        self.stream.write(data)
-                    start = end
-            elif breaks:
-                if ch not in '\n\x85\u2028\u2029':
-                    if text[start] == '\n':
-                        self.write_line_break()
-                    for br in text[start:end]:
-                        if br == '\n':
-                            self.write_line_break()
-                        else:
-                            self.write_line_break(br)
-                    self.write_indent()
-                    self.whitespace = False
-                    self.indention = False
-                    start = end
-            else:
-                if ch is None or ch in ' \n\x85\u2028\u2029':
-                    data = text[start:end]
-                    self.column += len(data)
-                    if self.encoding:
-                        data = data.encode(self.encoding)
-                    self.stream.write(data)
-                    start = end
-            if ch is not None:
-                spaces = (ch == ' ')
-                breaks = (ch in '\n\x85\u2028\u2029')
-            end += 1
diff --git a/third_party/python/PyYAML/lib3/yaml/error.py b/third_party/python/PyYAML/lib3/yaml/error.py
deleted file mode 100644
index b796b4dc51..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/error.py
+++ /dev/null
@@ -1,75 +0,0 @@
-
-__all__ = ['Mark', 'YAMLError', 'MarkedYAMLError']
-
-class Mark:
-
-    def __init__(self, name, index, line, column, buffer, pointer):
-        self.name = name
-        self.index = index
-        self.line = line
-        self.column = column
-        self.buffer = buffer
-        self.pointer = pointer
-
-    def get_snippet(self, indent=4, max_length=75):
-        if self.buffer is None:
-            return None
-        head = ''
-        start = self.pointer
-        while start > 0 and self.buffer[start-1] not in '\0\r\n\x85\u2028\u2029':
-            start -= 1
-            if self.pointer-start > max_length/2-1:
-                head = ' ... '
-                start += 5
-                break
-        tail = ''
-        end = self.pointer
-        while end < len(self.buffer) and self.buffer[end] not in '\0\r\n\x85\u2028\u2029':
-            end += 1
-            if end-self.pointer > max_length/2-1:
-                tail = ' ... '
-                end -= 5
-                break
-        snippet = self.buffer[start:end]
-        return ' '*indent + head + snippet + tail + '\n'  \
-                + ' '*(indent+self.pointer-start+len(head)) + '^'
-
-    def __str__(self):
-        snippet = self.get_snippet()
-        where = "  in \"%s\", line %d, column %d"   \
-                % (self.name, self.line+1, self.column+1)
-        if snippet is not None:
-            where += ":\n"+snippet
-        return where
-
-class YAMLError(Exception):
-    pass
-
-class MarkedYAMLError(YAMLError):
-
-    def __init__(self, context=None, context_mark=None,
-            problem=None, problem_mark=None, note=None):
-        self.context = context
-        self.context_mark = context_mark
-        self.problem = problem
-        self.problem_mark = problem_mark
-        self.note = note
-
-    def __str__(self):
-        lines = []
-        if self.context is not None:
-            lines.append(self.context)
-        if self.context_mark is not None  \
-            and (self.problem is None or self.problem_mark is None
-                    or self.context_mark.name != self.problem_mark.name
-                    or self.context_mark.line != self.problem_mark.line
-                    or self.context_mark.column != self.problem_mark.column):
-            lines.append(str(self.context_mark))
-        if self.problem is not None:
-            lines.append(self.problem)
-        if self.problem_mark is not None:
-            lines.append(str(self.problem_mark))
-        if self.note is not None:
-            lines.append(self.note)
-        return '\n'.join(lines)
-
diff --git a/third_party/python/PyYAML/lib3/yaml/events.py b/third_party/python/PyYAML/lib3/yaml/events.py
deleted file mode 100644
index f79ad389cb..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/events.py
+++ /dev/null
@@ -1,86 +0,0 @@
-
-# Abstract classes.
-
-class Event(object):
-    def __init__(self, start_mark=None, end_mark=None):
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-    def __repr__(self):
-        attributes = [key for key in ['anchor', 'tag', 'implicit', 'value']
-                if hasattr(self, key)]
-        arguments = ', '.join(['%s=%r' % (key, getattr(self, key))
-                for key in attributes])
-        return '%s(%s)' % (self.__class__.__name__, arguments)
-
-class NodeEvent(Event):
-    def __init__(self, anchor, start_mark=None, end_mark=None):
-        self.anchor = anchor
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-
-class CollectionStartEvent(NodeEvent):
-    def __init__(self, anchor, tag, implicit, start_mark=None, end_mark=None,
-            flow_style=None):
-        self.anchor = anchor
-        self.tag = tag
-        self.implicit = implicit
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.flow_style = flow_style
-
-class CollectionEndEvent(Event):
-    pass
-
-# Implementations.
-
-class StreamStartEvent(Event):
-    def __init__(self, start_mark=None, end_mark=None, encoding=None):
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.encoding = encoding
-
-class StreamEndEvent(Event):
-    pass
-
-class DocumentStartEvent(Event):
-    def __init__(self, start_mark=None, end_mark=None,
-            explicit=None, version=None, tags=None):
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.explicit = explicit
-        self.version = version
-        self.tags = tags
-
-class DocumentEndEvent(Event):
-    def __init__(self, start_mark=None, end_mark=None,
-            explicit=None):
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.explicit = explicit
-
-class AliasEvent(NodeEvent):
-    pass
-
-class ScalarEvent(NodeEvent):
-    def __init__(self, anchor, tag, implicit, value,
-            start_mark=None, end_mark=None, style=None):
-        self.anchor = anchor
-        self.tag = tag
-        self.implicit = implicit
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.style = style
-
-class SequenceStartEvent(CollectionStartEvent):
-    pass
-
-class SequenceEndEvent(CollectionEndEvent):
-    pass
-
-class MappingStartEvent(CollectionStartEvent):
-    pass
-
-class MappingEndEvent(CollectionEndEvent):
-    pass
-
diff --git a/third_party/python/PyYAML/lib3/yaml/loader.py b/third_party/python/PyYAML/lib3/yaml/loader.py
deleted file mode 100644
index e90c11224c..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/loader.py
+++ /dev/null
@@ -1,63 +0,0 @@
-
-__all__ = ['BaseLoader', 'FullLoader', 'SafeLoader', 'Loader', 'UnsafeLoader']
-
-from .reader import *
-from .scanner import *
-from .parser import *
-from .composer import *
-from .constructor import *
-from .resolver import *
-
-class BaseLoader(Reader, Scanner, Parser, Composer, BaseConstructor, BaseResolver):
-
-    def __init__(self, stream):
-        Reader.__init__(self, stream)
-        Scanner.__init__(self)
-        Parser.__init__(self)
-        Composer.__init__(self)
-        BaseConstructor.__init__(self)
-        BaseResolver.__init__(self)
-
-class FullLoader(Reader, Scanner, Parser, Composer, FullConstructor, Resolver):
-
-    def __init__(self, stream):
-        Reader.__init__(self, stream)
-        Scanner.__init__(self)
-        Parser.__init__(self)
-        Composer.__init__(self)
-        FullConstructor.__init__(self)
-        Resolver.__init__(self)
-
-class SafeLoader(Reader, Scanner, Parser, Composer, SafeConstructor, Resolver):
-
-    def __init__(self, stream):
-        Reader.__init__(self, stream)
-        Scanner.__init__(self)
-        Parser.__init__(self)
-        Composer.__init__(self)
-        SafeConstructor.__init__(self)
-        Resolver.__init__(self)
-
-class Loader(Reader, Scanner, Parser, Composer, Constructor, Resolver):
-
-    def __init__(self, stream):
-        Reader.__init__(self, stream)
-        Scanner.__init__(self)
-        Parser.__init__(self)
-        Composer.__init__(self)
-        Constructor.__init__(self)
-        Resolver.__init__(self)
-
-# UnsafeLoader is the same as Loader (which is and was always unsafe on
-# untrusted input). Use of either Loader or UnsafeLoader should be rare, since
-# FullLoad should be able to load almost all YAML safely. Loader is left intact
-# to ensure backwards compatibility.
-class UnsafeLoader(Reader, Scanner, Parser, Composer, Constructor, Resolver):
-
-    def __init__(self, stream):
-        Reader.__init__(self, stream)
-        Scanner.__init__(self)
-        Parser.__init__(self)
-        Composer.__init__(self)
-        Constructor.__init__(self)
-        Resolver.__init__(self)
diff --git a/third_party/python/PyYAML/lib3/yaml/nodes.py b/third_party/python/PyYAML/lib3/yaml/nodes.py
deleted file mode 100644
index c4f070c41e..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/nodes.py
+++ /dev/null
@@ -1,49 +0,0 @@
-
-class Node(object):
-    def __init__(self, tag, value, start_mark, end_mark):
-        self.tag = tag
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-    def __repr__(self):
-        value = self.value
-        #if isinstance(value, list):
-        #    if len(value) == 0:
-        #        value = '<empty>'
-        #    elif len(value) == 1:
-        #        value = '<1 item>'
-        #    else:
-        #        value = '<%d items>' % len(value)
-        #else:
-        #    if len(value) > 75:
-        #        value = repr(value[:70]+u' ... ')
-        #    else:
-        #        value = repr(value)
-        value = repr(value)
-        return '%s(tag=%r, value=%s)' % (self.__class__.__name__, self.tag, value)
-
-class ScalarNode(Node):
-    id = 'scalar'
-    def __init__(self, tag, value,
-            start_mark=None, end_mark=None, style=None):
-        self.tag = tag
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.style = style
-
-class CollectionNode(Node):
-    def __init__(self, tag, value,
-            start_mark=None, end_mark=None, flow_style=None):
-        self.tag = tag
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.flow_style = flow_style
-
-class SequenceNode(CollectionNode):
-    id = 'sequence'
-
-class MappingNode(CollectionNode):
-    id = 'mapping'
-
diff --git a/third_party/python/PyYAML/lib3/yaml/parser.py b/third_party/python/PyYAML/lib3/yaml/parser.py
deleted file mode 100644
index 13a5995d29..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/parser.py
+++ /dev/null
@@ -1,589 +0,0 @@
-
-# The following YAML grammar is LL(1) and is parsed by a recursive descent
-# parser.
-#
-# stream            ::= STREAM-START implicit_document? explicit_document* STREAM-END
-# implicit_document ::= block_node DOCUMENT-END*
-# explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
-# block_node_or_indentless_sequence ::=
-#                       ALIAS
-#                       | properties (block_content | indentless_block_sequence)?
-#                       | block_content
-#                       | indentless_block_sequence
-# block_node        ::= ALIAS
-#                       | properties block_content?
-#                       | block_content
-# flow_node         ::= ALIAS
-#                       | properties flow_content?
-#                       | flow_content
-# properties        ::= TAG ANCHOR? | ANCHOR TAG?
-# block_content     ::= block_collection | flow_collection | SCALAR
-# flow_content      ::= flow_collection | SCALAR
-# block_collection  ::= block_sequence | block_mapping
-# flow_collection   ::= flow_sequence | flow_mapping
-# block_sequence    ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
-# indentless_sequence   ::= (BLOCK-ENTRY block_node?)+
-# block_mapping     ::= BLOCK-MAPPING_START
-#                       ((KEY block_node_or_indentless_sequence?)?
-#                       (VALUE block_node_or_indentless_sequence?)?)*
-#                       BLOCK-END
-# flow_sequence     ::= FLOW-SEQUENCE-START
-#                       (flow_sequence_entry FLOW-ENTRY)*
-#                       flow_sequence_entry?
-#                       FLOW-SEQUENCE-END
-# flow_sequence_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
-# flow_mapping      ::= FLOW-MAPPING-START
-#                       (flow_mapping_entry FLOW-ENTRY)*
-#                       flow_mapping_entry?
-#                       FLOW-MAPPING-END
-# flow_mapping_entry    ::= flow_node | KEY flow_node? (VALUE flow_node?)?
-#
-# FIRST sets:
-#
-# stream: { STREAM-START }
-# explicit_document: { DIRECTIVE DOCUMENT-START }
-# implicit_document: FIRST(block_node)
-# block_node: { ALIAS TAG ANCHOR SCALAR BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START }
-# flow_node: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START }
-# block_content: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
-# flow_content: { FLOW-SEQUENCE-START FLOW-MAPPING-START SCALAR }
-# block_collection: { BLOCK-SEQUENCE-START BLOCK-MAPPING-START }
-# flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
-# block_sequence: { BLOCK-SEQUENCE-START }
-# block_mapping: { BLOCK-MAPPING-START }
-# block_node_or_indentless_sequence: { ALIAS ANCHOR TAG SCALAR BLOCK-SEQUENCE-START BLOCK-MAPPING-START FLOW-SEQUENCE-START FLOW-MAPPING-START BLOCK-ENTRY }
-# indentless_sequence: { ENTRY }
-# flow_collection: { FLOW-SEQUENCE-START FLOW-MAPPING-START }
-# flow_sequence: { FLOW-SEQUENCE-START }
-# flow_mapping: { FLOW-MAPPING-START }
-# flow_sequence_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START KEY }
-# flow_mapping_entry: { ALIAS ANCHOR TAG SCALAR FLOW-SEQUENCE-START FLOW-MAPPING-START KEY }
-
-__all__ = ['Parser', 'ParserError']
-
-from .error import MarkedYAMLError
-from .tokens import *
-from .events import *
-from .scanner import *
-
-class ParserError(MarkedYAMLError):
-    pass
-
-class Parser:
-    # Since writing a recursive-descendant parser is a straightforward task, we
-    # do not give many comments here.
-
-    DEFAULT_TAGS = {
-        '!':   '!',
-        '!!':  'tag:yaml.org,2002:',
-    }
-
-    def __init__(self):
-        self.current_event = None
-        self.yaml_version = None
-        self.tag_handles = {}
-        self.states = []
-        self.marks = []
-        self.state = self.parse_stream_start
-
-    def dispose(self):
-        # Reset the state attributes (to clear self-references)
-        self.states = []
-        self.state = None
-
-    def check_event(self, *choices):
-        # Check the type of the next event.
-        if self.current_event is None:
-            if self.state:
-                self.current_event = self.state()
-        if self.current_event is not None:
-            if not choices:
-                return True
-            for choice in choices:
-                if isinstance(self.current_event, choice):
-                    return True
-        return False
-
-    def peek_event(self):
-        # Get the next event.
-        if self.current_event is None:
-            if self.state:
-                self.current_event = self.state()
-        return self.current_event
-
-    def get_event(self):
-        # Get the next event and proceed further.
-        if self.current_event is None:
-            if self.state:
-                self.current_event = self.state()
-        value = self.current_event
-        self.current_event = None
-        return value
-
-    # stream    ::= STREAM-START implicit_document? explicit_document* STREAM-END
-    # implicit_document ::= block_node DOCUMENT-END*
-    # explicit_document ::= DIRECTIVE* DOCUMENT-START block_node? DOCUMENT-END*
-
-    def parse_stream_start(self):
-
-        # Parse the stream start.
-        token = self.get_token()
-        event = StreamStartEvent(token.start_mark, token.end_mark,
-                encoding=token.encoding)
-
-        # Prepare the next state.
-        self.state = self.parse_implicit_document_start
-
-        return event
-
-    def parse_implicit_document_start(self):
-
-        # Parse an implicit document.
-        if not self.check_token(DirectiveToken, DocumentStartToken,
-                StreamEndToken):
-            self.tag_handles = self.DEFAULT_TAGS
-            token = self.peek_token()
-            start_mark = end_mark = token.start_mark
-            event = DocumentStartEvent(start_mark, end_mark,
-                    explicit=False)
-
-            # Prepare the next state.
-            self.states.append(self.parse_document_end)
-            self.state = self.parse_block_node
-
-            return event
-
-        else:
-            return self.parse_document_start()
-
-    def parse_document_start(self):
-
-        # Parse any extra document end indicators.
-        while self.check_token(DocumentEndToken):
-            self.get_token()
-
-        # Parse an explicit document.
-        if not self.check_token(StreamEndToken):
-            token = self.peek_token()
-            start_mark = token.start_mark
-            version, tags = self.process_directives()
-            if not self.check_token(DocumentStartToken):
-                raise ParserError(None, None,
-                        "expected '<document start>', but found %r"
-                        % self.peek_token().id,
-                        self.peek_token().start_mark)
-            token = self.get_token()
-            end_mark = token.end_mark
-            event = DocumentStartEvent(start_mark, end_mark,
-                    explicit=True, version=version, tags=tags)
-            self.states.append(self.parse_document_end)
-            self.state = self.parse_document_content
-        else:
-            # Parse the end of the stream.
-            token = self.get_token()
-            event = StreamEndEvent(token.start_mark, token.end_mark)
-            assert not self.states
-            assert not self.marks
-            self.state = None
-        return event
-
-    def parse_document_end(self):
-
-        # Parse the document end.
-        token = self.peek_token()
-        start_mark = end_mark = token.start_mark
-        explicit = False
-        if self.check_token(DocumentEndToken):
-            token = self.get_token()
-            end_mark = token.end_mark
-            explicit = True
-        event = DocumentEndEvent(start_mark, end_mark,
-                explicit=explicit)
-
-        # Prepare the next state.
-        self.state = self.parse_document_start
-
-        return event
-
-    def parse_document_content(self):
-        if self.check_token(DirectiveToken,
-                DocumentStartToken, DocumentEndToken, StreamEndToken):
-            event = self.process_empty_scalar(self.peek_token().start_mark)
-            self.state = self.states.pop()
-            return event
-        else:
-            return self.parse_block_node()
-
-    def process_directives(self):
-        self.yaml_version = None
-        self.tag_handles = {}
-        while self.check_token(DirectiveToken):
-            token = self.get_token()
-            if token.name == 'YAML':
-                if self.yaml_version is not None:
-                    raise ParserError(None, None,
-                            "found duplicate YAML directive", token.start_mark)
-                major, minor = token.value
-                if major != 1:
-                    raise ParserError(None, None,
-                            "found incompatible YAML document (version 1.* is required)",
-                            token.start_mark)
-                self.yaml_version = token.value
-            elif token.name == 'TAG':
-                handle, prefix = token.value
-                if handle in self.tag_handles:
-                    raise ParserError(None, None,
-                            "duplicate tag handle %r" % handle,
-                            token.start_mark)
-                self.tag_handles[handle] = prefix
-        if self.tag_handles:
-            value = self.yaml_version, self.tag_handles.copy()
-        else:
-            value = self.yaml_version, None
-        for key in self.DEFAULT_TAGS:
-            if key not in self.tag_handles:
-                self.tag_handles[key] = self.DEFAULT_TAGS[key]
-        return value
-
-    # block_node_or_indentless_sequence ::= ALIAS
-    #               | properties (block_content | indentless_block_sequence)?
-    #               | block_content
-    #               | indentless_block_sequence
-    # block_node    ::= ALIAS
-    #                   | properties block_content?
-    #                   | block_content
-    # flow_node     ::= ALIAS
-    #                   | properties flow_content?
-    #                   | flow_content
-    # properties    ::= TAG ANCHOR? | ANCHOR TAG?
-    # block_content     ::= block_collection | flow_collection | SCALAR
-    # flow_content      ::= flow_collection | SCALAR
-    # block_collection  ::= block_sequence | block_mapping
-    # flow_collection   ::= flow_sequence | flow_mapping
-
-    def parse_block_node(self):
-        return self.parse_node(block=True)
-
-    def parse_flow_node(self):
-        return self.parse_node()
-
-    def parse_block_node_or_indentless_sequence(self):
-        return self.parse_node(block=True, indentless_sequence=True)
-
-    def parse_node(self, block=False, indentless_sequence=False):
-        if self.check_token(AliasToken):
-            token = self.get_token()
-            event = AliasEvent(token.value, token.start_mark, token.end_mark)
-            self.state = self.states.pop()
-        else:
-            anchor = None
-            tag = None
-            start_mark = end_mark = tag_mark = None
-            if self.check_token(AnchorToken):
-                token = self.get_token()
-                start_mark = token.start_mark
-                end_mark = token.end_mark
-                anchor = token.value
-                if self.check_token(TagToken):
-                    token = self.get_token()
-                    tag_mark = token.start_mark
-                    end_mark = token.end_mark
-                    tag = token.value
-            elif self.check_token(TagToken):
-                token = self.get_token()
-                start_mark = tag_mark = token.start_mark
-                end_mark = token.end_mark
-                tag = token.value
-                if self.check_token(AnchorToken):
-                    token = self.get_token()
-                    end_mark = token.end_mark
-                    anchor = token.value
-            if tag is not None:
-                handle, suffix = tag
-                if handle is not None:
-                    if handle not in self.tag_handles:
-                        raise ParserError("while parsing a node", start_mark,
-                                "found undefined tag handle %r" % handle,
-                                tag_mark)
-                    tag = self.tag_handles[handle]+suffix
-                else:
-                    tag = suffix
-            #if tag == '!':
-            #    raise ParserError("while parsing a node", start_mark,
-            #            "found non-specific tag '!'", tag_mark,
-            #            "Please check 'http://pyyaml.org/wiki/YAMLNonSpecificTag' and share your opinion.")
-            if start_mark is None:
-                start_mark = end_mark = self.peek_token().start_mark
-            event = None
-            implicit = (tag is None or tag == '!')
-            if indentless_sequence and self.check_token(BlockEntryToken):
-                end_mark = self.peek_token().end_mark
-                event = SequenceStartEvent(anchor, tag, implicit,
-                        start_mark, end_mark)
-                self.state = self.parse_indentless_sequence_entry
-            else:
-                if self.check_token(ScalarToken):
-                    token = self.get_token()
-                    end_mark = token.end_mark
-                    if (token.plain and tag is None) or tag == '!':
-                        implicit = (True, False)
-                    elif tag is None:
-                        implicit = (False, True)
-                    else:
-                        implicit = (False, False)
-                    event = ScalarEvent(anchor, tag, implicit, token.value,
-                            start_mark, end_mark, style=token.style)
-                    self.state = self.states.pop()
-                elif self.check_token(FlowSequenceStartToken):
-                    end_mark = self.peek_token().end_mark
-                    event = SequenceStartEvent(anchor, tag, implicit,
-                            start_mark, end_mark, flow_style=True)
-                    self.state = self.parse_flow_sequence_first_entry
-                elif self.check_token(FlowMappingStartToken):
-                    end_mark = self.peek_token().end_mark
-                    event = MappingStartEvent(anchor, tag, implicit,
-                            start_mark, end_mark, flow_style=True)
-                    self.state = self.parse_flow_mapping_first_key
-                elif block and self.check_token(BlockSequenceStartToken):
-                    end_mark = self.peek_token().start_mark
-                    event = SequenceStartEvent(anchor, tag, implicit,
-                            start_mark, end_mark, flow_style=False)
-                    self.state = self.parse_block_sequence_first_entry
-                elif block and self.check_token(BlockMappingStartToken):
-                    end_mark = self.peek_token().start_mark
-                    event = MappingStartEvent(anchor, tag, implicit,
-                            start_mark, end_mark, flow_style=False)
-                    self.state = self.parse_block_mapping_first_key
-                elif anchor is not None or tag is not None:
-                    # Empty scalars are allowed even if a tag or an anchor is
-                    # specified.
-                    event = ScalarEvent(anchor, tag, (implicit, False), '',
-                            start_mark, end_mark)
-                    self.state = self.states.pop()
-                else:
-                    if block:
-                        node = 'block'
-                    else:
-                        node = 'flow'
-                    token = self.peek_token()
-                    raise ParserError("while parsing a %s node" % node, start_mark,
-                            "expected the node content, but found %r" % token.id,
-                            token.start_mark)
-        return event
-
-    # block_sequence ::= BLOCK-SEQUENCE-START (BLOCK-ENTRY block_node?)* BLOCK-END
-
-    def parse_block_sequence_first_entry(self):
-        token = self.get_token()
-        self.marks.append(token.start_mark)
-        return self.parse_block_sequence_entry()
-
-    def parse_block_sequence_entry(self):
-        if self.check_token(BlockEntryToken):
-            token = self.get_token()
-            if not self.check_token(BlockEntryToken, BlockEndToken):
-                self.states.append(self.parse_block_sequence_entry)
-                return self.parse_block_node()
-            else:
-                self.state = self.parse_block_sequence_entry
-                return self.process_empty_scalar(token.end_mark)
-        if not self.check_token(BlockEndToken):
-            token = self.peek_token()
-            raise ParserError("while parsing a block collection", self.marks[-1],
-                    "expected <block end>, but found %r" % token.id, token.start_mark)
-        token = self.get_token()
-        event = SequenceEndEvent(token.start_mark, token.end_mark)
-        self.state = self.states.pop()
-        self.marks.pop()
-        return event
-
-    # indentless_sequence ::= (BLOCK-ENTRY block_node?)+
-
-    def parse_indentless_sequence_entry(self):
-        if self.check_token(BlockEntryToken):
-            token = self.get_token()
-            if not self.check_token(BlockEntryToken,
-                    KeyToken, ValueToken, BlockEndToken):
-                self.states.append(self.parse_indentless_sequence_entry)
-                return self.parse_block_node()
-            else:
-                self.state = self.parse_indentless_sequence_entry
-                return self.process_empty_scalar(token.end_mark)
-        token = self.peek_token()
-        event = SequenceEndEvent(token.start_mark, token.start_mark)
-        self.state = self.states.pop()
-        return event
-
-    # block_mapping     ::= BLOCK-MAPPING_START
-    #                       ((KEY block_node_or_indentless_sequence?)?
-    #                       (VALUE block_node_or_indentless_sequence?)?)*
-    #                       BLOCK-END
-
-    def parse_block_mapping_first_key(self):
-        token = self.get_token()
-        self.marks.append(token.start_mark)
-        return self.parse_block_mapping_key()
-
-    def parse_block_mapping_key(self):
-        if self.check_token(KeyToken):
-            token = self.get_token()
-            if not self.check_token(KeyToken, ValueToken, BlockEndToken):
-                self.states.append(self.parse_block_mapping_value)
-                return self.parse_block_node_or_indentless_sequence()
-            else:
-                self.state = self.parse_block_mapping_value
-                return self.process_empty_scalar(token.end_mark)
-        if not self.check_token(BlockEndToken):
-            token = self.peek_token()
-            raise ParserError("while parsing a block mapping", self.marks[-1],
-                    "expected <block end>, but found %r" % token.id, token.start_mark)
-        token = self.get_token()
-        event = MappingEndEvent(token.start_mark, token.end_mark)
-        self.state = self.states.pop()
-        self.marks.pop()
-        return event
-
-    def parse_block_mapping_value(self):
-        if self.check_token(ValueToken):
-            token = self.get_token()
-            if not self.check_token(KeyToken, ValueToken, BlockEndToken):
-                self.states.append(self.parse_block_mapping_key)
-                return self.parse_block_node_or_indentless_sequence()
-            else:
-                self.state = self.parse_block_mapping_key
-                return self.process_empty_scalar(token.end_mark)
-        else:
-            self.state = self.parse_block_mapping_key
-            token = self.peek_token()
-            return self.process_empty_scalar(token.start_mark)
-
-    # flow_sequence     ::= FLOW-SEQUENCE-START
-    #                       (flow_sequence_entry FLOW-ENTRY)*
-    #                       flow_sequence_entry?
-    #                       FLOW-SEQUENCE-END
-    # flow_sequence_entry   ::= flow_node | KEY flow_node? (VALUE flow_node?)?
-    #
-    # Note that while production rules for both flow_sequence_entry and
-    # flow_mapping_entry are equal, their interpretations are different.
-    # For `flow_sequence_entry`, the part `KEY flow_node? (VALUE flow_node?)?`
-    # generate an inline mapping (set syntax).
-
-    def parse_flow_sequence_first_entry(self):
-        token = self.get_token()
-        self.marks.append(token.start_mark)
-        return self.parse_flow_sequence_entry(first=True)
-
-    def parse_flow_sequence_entry(self, first=False):
-        if not self.check_token(FlowSequenceEndToken):
-            if not first:
-                if self.check_token(FlowEntryToken):
-                    self.get_token()
-                else:
-                    token = self.peek_token()
-                    raise ParserError("while parsing a flow sequence", self.marks[-1],
-                            "expected ',' or ']', but got %r" % token.id, token.start_mark)
-            
-            if self.check_token(KeyToken):
-                token = self.peek_token()
-                event = MappingStartEvent(None, None, True,
-                        token.start_mark, token.end_mark,
-                        flow_style=True)
-                self.state = self.parse_flow_sequence_entry_mapping_key
-                return event
-            elif not self.check_token(FlowSequenceEndToken):
-                self.states.append(self.parse_flow_sequence_entry)
-                return self.parse_flow_node()
-        token = self.get_token()
-        event = SequenceEndEvent(token.start_mark, token.end_mark)
-        self.state = self.states.pop()
-        self.marks.pop()
-        return event
-
-    def parse_flow_sequence_entry_mapping_key(self):
-        token = self.get_token()
-        if not self.check_token(ValueToken,
-                FlowEntryToken, FlowSequenceEndToken):
-            self.states.append(self.parse_flow_sequence_entry_mapping_value)
-            return self.parse_flow_node()
-        else:
-            self.state = self.parse_flow_sequence_entry_mapping_value
-            return self.process_empty_scalar(token.end_mark)
-
-    def parse_flow_sequence_entry_mapping_value(self):
-        if self.check_token(ValueToken):
-            token = self.get_token()
-            if not self.check_token(FlowEntryToken, FlowSequenceEndToken):
-                self.states.append(self.parse_flow_sequence_entry_mapping_end)
-                return self.parse_flow_node()
-            else:
-                self.state = self.parse_flow_sequence_entry_mapping_end
-                return self.process_empty_scalar(token.end_mark)
-        else:
-            self.state = self.parse_flow_sequence_entry_mapping_end
-            token = self.peek_token()
-            return self.process_empty_scalar(token.start_mark)
-
-    def parse_flow_sequence_entry_mapping_end(self):
-        self.state = self.parse_flow_sequence_entry
-        token = self.peek_token()
-        return MappingEndEvent(token.start_mark, token.start_mark)
-
-    # flow_mapping  ::= FLOW-MAPPING-START
-    #                   (flow_mapping_entry FLOW-ENTRY)*
-    #                   flow_mapping_entry?
-    #                   FLOW-MAPPING-END
-    # flow_mapping_entry    ::= flow_node | KEY flow_node? (VALUE flow_node?)?
-
-    def parse_flow_mapping_first_key(self):
-        token = self.get_token()
-        self.marks.append(token.start_mark)
-        return self.parse_flow_mapping_key(first=True)
-
-    def parse_flow_mapping_key(self, first=False):
-        if not self.check_token(FlowMappingEndToken):
-            if not first:
-                if self.check_token(FlowEntryToken):
-                    self.get_token()
-                else:
-                    token = self.peek_token()
-                    raise ParserError("while parsing a flow mapping", self.marks[-1],
-                            "expected ',' or '}', but got %r" % token.id, token.start_mark)
-            if self.check_token(KeyToken):
-                token = self.get_token()
-                if not self.check_token(ValueToken,
-                        FlowEntryToken, FlowMappingEndToken):
-                    self.states.append(self.parse_flow_mapping_value)
-                    return self.parse_flow_node()
-                else:
-                    self.state = self.parse_flow_mapping_value
-                    return self.process_empty_scalar(token.end_mark)
-            elif not self.check_token(FlowMappingEndToken):
-                self.states.append(self.parse_flow_mapping_empty_value)
-                return self.parse_flow_node()
-        token = self.get_token()
-        event = MappingEndEvent(token.start_mark, token.end_mark)
-        self.state = self.states.pop()
-        self.marks.pop()
-        return event
-
-    def parse_flow_mapping_value(self):
-        if self.check_token(ValueToken):
-            token = self.get_token()
-            if not self.check_token(FlowEntryToken, FlowMappingEndToken):
-                self.states.append(self.parse_flow_mapping_key)
-                return self.parse_flow_node()
-            else:
-                self.state = self.parse_flow_mapping_key
-                return self.process_empty_scalar(token.end_mark)
-        else:
-            self.state = self.parse_flow_mapping_key
-            token = self.peek_token()
-            return self.process_empty_scalar(token.start_mark)
-
-    def parse_flow_mapping_empty_value(self):
-        self.state = self.parse_flow_mapping_key
-        return self.process_empty_scalar(self.peek_token().start_mark)
-
-    def process_empty_scalar(self, mark):
-        return ScalarEvent(None, None, (True, False), '', mark, mark)
-
diff --git a/third_party/python/PyYAML/lib3/yaml/reader.py b/third_party/python/PyYAML/lib3/yaml/reader.py
deleted file mode 100644
index 774b0219b5..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/reader.py
+++ /dev/null
@@ -1,185 +0,0 @@
-# This module contains abstractions for the input stream. You don't have to
-# looks further, there are no pretty code.
-#
-# We define two classes here.
-#
-#   Mark(source, line, column)
-# It's just a record and its only use is producing nice error messages.
-# Parser does not use it for any other purposes.
-#
-#   Reader(source, data)
-# Reader determines the encoding of `data` and converts it to unicode.
-# Reader provides the following methods and attributes:
-#   reader.peek(length=1) - return the next `length` characters
-#   reader.forward(length=1) - move the current position to `length` characters.
-#   reader.index - the number of the current character.
-#   reader.line, stream.column - the line and the column of the current character.
-
-__all__ = ['Reader', 'ReaderError']
-
-from .error import YAMLError, Mark
-
-import codecs, re
-
-class ReaderError(YAMLError):
-
-    def __init__(self, name, position, character, encoding, reason):
-        self.name = name
-        self.character = character
-        self.position = position
-        self.encoding = encoding
-        self.reason = reason
-
-    def __str__(self):
-        if isinstance(self.character, bytes):
-            return "'%s' codec can't decode byte #x%02x: %s\n"  \
-                    "  in \"%s\", position %d"    \
-                    % (self.encoding, ord(self.character), self.reason,
-                            self.name, self.position)
-        else:
-            return "unacceptable character #x%04x: %s\n"    \
-                    "  in \"%s\", position %d"    \
-                    % (self.character, self.reason,
-                            self.name, self.position)
-
-class Reader(object):
-    # Reader:
-    # - determines the data encoding and converts it to a unicode string,
-    # - checks if characters are in allowed range,
-    # - adds '\0' to the end.
-
-    # Reader accepts
-    #  - a `bytes` object,
-    #  - a `str` object,
-    #  - a file-like object with its `read` method returning `str`,
-    #  - a file-like object with its `read` method returning `unicode`.
-
-    # Yeah, it's ugly and slow.
-
-    def __init__(self, stream):
-        self.name = None
-        self.stream = None
-        self.stream_pointer = 0
-        self.eof = True
-        self.buffer = ''
-        self.pointer = 0
-        self.raw_buffer = None
-        self.raw_decode = None
-        self.encoding = None
-        self.index = 0
-        self.line = 0
-        self.column = 0
-        if isinstance(stream, str):
-            self.name = "<unicode string>"
-            self.check_printable(stream)
-            self.buffer = stream+'\0'
-        elif isinstance(stream, bytes):
-            self.name = "<byte string>"
-            self.raw_buffer = stream
-            self.determine_encoding()
-        else:
-            self.stream = stream
-            self.name = getattr(stream, 'name', "<file>")
-            self.eof = False
-            self.raw_buffer = None
-            self.determine_encoding()
-
-    def peek(self, index=0):
-        try:
-            return self.buffer[self.pointer+index]
-        except IndexError:
-            self.update(index+1)
-            return self.buffer[self.pointer+index]
-
-    def prefix(self, length=1):
-        if self.pointer+length >= len(self.buffer):
-            self.update(length)
-        return self.buffer[self.pointer:self.pointer+length]
-
-    def forward(self, length=1):
-        if self.pointer+length+1 >= len(self.buffer):
-            self.update(length+1)
-        while length:
-            ch = self.buffer[self.pointer]
-            self.pointer += 1
-            self.index += 1
-            if ch in '\n\x85\u2028\u2029'  \
-                    or (ch == '\r' and self.buffer[self.pointer] != '\n'):
-                self.line += 1
-                self.column = 0
-            elif ch != '\uFEFF':
-                self.column += 1
-            length -= 1
-
-    def get_mark(self):
-        if self.stream is None:
-            return Mark(self.name, self.index, self.line, self.column,
-                    self.buffer, self.pointer)
-        else:
-            return Mark(self.name, self.index, self.line, self.column,
-                    None, None)
-
-    def determine_encoding(self):
-        while not self.eof and (self.raw_buffer is None or len(self.raw_buffer) < 2):
-            self.update_raw()
-        if isinstance(self.raw_buffer, bytes):
-            if self.raw_buffer.startswith(codecs.BOM_UTF16_LE):
-                self.raw_decode = codecs.utf_16_le_decode
-                self.encoding = 'utf-16-le'
-            elif self.raw_buffer.startswith(codecs.BOM_UTF16_BE):
-                self.raw_decode = codecs.utf_16_be_decode
-                self.encoding = 'utf-16-be'
-            else:
-                self.raw_decode = codecs.utf_8_decode
-                self.encoding = 'utf-8'
-        self.update(1)
-
-    NON_PRINTABLE = re.compile('[^\x09\x0A\x0D\x20-\x7E\x85\xA0-\uD7FF\uE000-\uFFFD\U00010000-\U0010ffff]')
-    def check_printable(self, data):
-        match = self.NON_PRINTABLE.search(data)
-        if match:
-            character = match.group()
-            position = self.index+(len(self.buffer)-self.pointer)+match.start()
-            raise ReaderError(self.name, position, ord(character),
-                    'unicode', "special characters are not allowed")
-
-    def update(self, length):
-        if self.raw_buffer is None:
-            return
-        self.buffer = self.buffer[self.pointer:]
-        self.pointer = 0
-        while len(self.buffer) < length:
-            if not self.eof:
-                self.update_raw()
-            if self.raw_decode is not None:
-                try:
-                    data, converted = self.raw_decode(self.raw_buffer,
-                            'strict', self.eof)
-                except UnicodeDecodeError as exc:
-                    character = self.raw_buffer[exc.start]
-                    if self.stream is not None:
-                        position = self.stream_pointer-len(self.raw_buffer)+exc.start
-                    else:
-                        position = exc.start
-                    raise ReaderError(self.name, position, character,
-                            exc.encoding, exc.reason)
-            else:
-                data = self.raw_buffer
-                converted = len(data)
-            self.check_printable(data)
-            self.buffer += data
-            self.raw_buffer = self.raw_buffer[converted:]
-            if self.eof:
-                self.buffer += '\0'
-                self.raw_buffer = None
-                break
-
-    def update_raw(self, size=4096):
-        data = self.stream.read(size)
-        if self.raw_buffer is None:
-            self.raw_buffer = data
-        else:
-            self.raw_buffer += data
-        self.stream_pointer += len(data)
-        if not data:
-            self.eof = True
diff --git a/third_party/python/PyYAML/lib3/yaml/representer.py b/third_party/python/PyYAML/lib3/yaml/representer.py
deleted file mode 100644
index 3b0b192ef3..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/representer.py
+++ /dev/null
@@ -1,389 +0,0 @@
-
-__all__ = ['BaseRepresenter', 'SafeRepresenter', 'Representer',
-    'RepresenterError']
-
-from .error import *
-from .nodes import *
-
-import datetime, copyreg, types, base64, collections
-
-class RepresenterError(YAMLError):
-    pass
-
-class BaseRepresenter:
-
-    yaml_representers = {}
-    yaml_multi_representers = {}
-
-    def __init__(self, default_style=None, default_flow_style=False, sort_keys=True):
-        self.default_style = default_style
-        self.sort_keys = sort_keys
-        self.default_flow_style = default_flow_style
-        self.represented_objects = {}
-        self.object_keeper = []
-        self.alias_key = None
-
-    def represent(self, data):
-        node = self.represent_data(data)
-        self.serialize(node)
-        self.represented_objects = {}
-        self.object_keeper = []
-        self.alias_key = None
-
-    def represent_data(self, data):
-        if self.ignore_aliases(data):
-            self.alias_key = None
-        else:
-            self.alias_key = id(data)
-        if self.alias_key is not None:
-            if self.alias_key in self.represented_objects:
-                node = self.represented_objects[self.alias_key]
-                #if node is None:
-                #    raise RepresenterError("recursive objects are not allowed: %r" % data)
-                return node
-            #self.represented_objects[alias_key] = None
-            self.object_keeper.append(data)
-        data_types = type(data).__mro__
-        if data_types[0] in self.yaml_representers:
-            node = self.yaml_representers[data_types[0]](self, data)
-        else:
-            for data_type in data_types:
-                if data_type in self.yaml_multi_representers:
-                    node = self.yaml_multi_representers[data_type](self, data)
-                    break
-            else:
-                if None in self.yaml_multi_representers:
-                    node = self.yaml_multi_representers[None](self, data)
-                elif None in self.yaml_representers:
-                    node = self.yaml_representers[None](self, data)
-                else:
-                    node = ScalarNode(None, str(data))
-        #if alias_key is not None:
-        #    self.represented_objects[alias_key] = node
-        return node
-
-    @classmethod
-    def add_representer(cls, data_type, representer):
-        if not 'yaml_representers' in cls.__dict__:
-            cls.yaml_representers = cls.yaml_representers.copy()
-        cls.yaml_representers[data_type] = representer
-
-    @classmethod
-    def add_multi_representer(cls, data_type, representer):
-        if not 'yaml_multi_representers' in cls.__dict__:
-            cls.yaml_multi_representers = cls.yaml_multi_representers.copy()
-        cls.yaml_multi_representers[data_type] = representer
-
-    def represent_scalar(self, tag, value, style=None):
-        if style is None:
-            style = self.default_style
-        node = ScalarNode(tag, value, style=style)
-        if self.alias_key is not None:
-            self.represented_objects[self.alias_key] = node
-        return node
-
-    def represent_sequence(self, tag, sequence, flow_style=None):
-        value = []
-        node = SequenceNode(tag, value, flow_style=flow_style)
-        if self.alias_key is not None:
-            self.represented_objects[self.alias_key] = node
-        best_style = True
-        for item in sequence:
-            node_item = self.represent_data(item)
-            if not (isinstance(node_item, ScalarNode) and not node_item.style):
-                best_style = False
-            value.append(node_item)
-        if flow_style is None:
-            if self.default_flow_style is not None:
-                node.flow_style = self.default_flow_style
-            else:
-                node.flow_style = best_style
-        return node
-
-    def represent_mapping(self, tag, mapping, flow_style=None):
-        value = []
-        node = MappingNode(tag, value, flow_style=flow_style)
-        if self.alias_key is not None:
-            self.represented_objects[self.alias_key] = node
-        best_style = True
-        if hasattr(mapping, 'items'):
-            mapping = list(mapping.items())
-            if self.sort_keys:
-                try:
-                    mapping = sorted(mapping)
-                except TypeError:
-                    pass
-        for item_key, item_value in mapping:
-            node_key = self.represent_data(item_key)
-            node_value = self.represent_data(item_value)
-            if not (isinstance(node_key, ScalarNode) and not node_key.style):
-                best_style = False
-            if not (isinstance(node_value, ScalarNode) and not node_value.style):
-                best_style = False
-            value.append((node_key, node_value))
-        if flow_style is None:
-            if self.default_flow_style is not None:
-                node.flow_style = self.default_flow_style
-            else:
-                node.flow_style = best_style
-        return node
-
-    def ignore_aliases(self, data):
-        return False
-
-class SafeRepresenter(BaseRepresenter):
-
-    def ignore_aliases(self, data):
-        if data is None:
-            return True
-        if isinstance(data, tuple) and data == ():
-            return True
-        if isinstance(data, (str, bytes, bool, int, float)):
-            return True
-
-    def represent_none(self, data):
-        return self.represent_scalar('tag:yaml.org,2002:null', 'null')
-
-    def represent_str(self, data):
-        return self.represent_scalar('tag:yaml.org,2002:str', data)
-
-    def represent_binary(self, data):
-        if hasattr(base64, 'encodebytes'):
-            data = base64.encodebytes(data).decode('ascii')
-        else:
-            data = base64.encodestring(data).decode('ascii')
-        return self.represent_scalar('tag:yaml.org,2002:binary', data, style='|')
-
-    def represent_bool(self, data):
-        if data:
-            value = 'true'
-        else:
-            value = 'false'
-        return self.represent_scalar('tag:yaml.org,2002:bool', value)
-
-    def represent_int(self, data):
-        return self.represent_scalar('tag:yaml.org,2002:int', str(data))
-
-    inf_value = 1e300
-    while repr(inf_value) != repr(inf_value*inf_value):
-        inf_value *= inf_value
-
-    def represent_float(self, data):
-        if data != data or (data == 0.0 and data == 1.0):
-            value = '.nan'
-        elif data == self.inf_value:
-            value = '.inf'
-        elif data == -self.inf_value:
-            value = '-.inf'
-        else:
-            value = repr(data).lower()
-            # Note that in some cases `repr(data)` represents a float number
-            # without the decimal parts.  For instance:
-            #   >>> repr(1e17)
-            #   '1e17'
-            # Unfortunately, this is not a valid float representation according
-            # to the definition of the `!!float` tag.  We fix this by adding
-            # '.0' before the 'e' symbol.
-            if '.' not in value and 'e' in value:
-                value = value.replace('e', '.0e', 1)
-        return self.represent_scalar('tag:yaml.org,2002:float', value)
-
-    def represent_list(self, data):
-        #pairs = (len(data) > 0 and isinstance(data, list))
-        #if pairs:
-        #    for item in data:
-        #        if not isinstance(item, tuple) or len(item) != 2:
-        #            pairs = False
-        #            break
-        #if not pairs:
-            return self.represent_sequence('tag:yaml.org,2002:seq', data)
-        #value = []
-        #for item_key, item_value in data:
-        #    value.append(self.represent_mapping(u'tag:yaml.org,2002:map',
-        #        [(item_key, item_value)]))
-        #return SequenceNode(u'tag:yaml.org,2002:pairs', value)
-
-    def represent_dict(self, data):
-        return self.represent_mapping('tag:yaml.org,2002:map', data)
-
-    def represent_set(self, data):
-        value = {}
-        for key in data:
-            value[key] = None
-        return self.represent_mapping('tag:yaml.org,2002:set', value)
-
-    def represent_date(self, data):
-        value = data.isoformat()
-        return self.represent_scalar('tag:yaml.org,2002:timestamp', value)
-
-    def represent_datetime(self, data):
-        value = data.isoformat(' ')
-        return self.represent_scalar('tag:yaml.org,2002:timestamp', value)
-
-    def represent_yaml_object(self, tag, data, cls, flow_style=None):
-        if hasattr(data, '__getstate__'):
-            state = data.__getstate__()
-        else:
-            state = data.__dict__.copy()
-        return self.represent_mapping(tag, state, flow_style=flow_style)
-
-    def represent_undefined(self, data):
-        raise RepresenterError("cannot represent an object", data)
-
-SafeRepresenter.add_representer(type(None),
-        SafeRepresenter.represent_none)
-
-SafeRepresenter.add_representer(str,
-        SafeRepresenter.represent_str)
-
-SafeRepresenter.add_representer(bytes,
-        SafeRepresenter.represent_binary)
-
-SafeRepresenter.add_representer(bool,
-        SafeRepresenter.represent_bool)
-
-SafeRepresenter.add_representer(int,
-        SafeRepresenter.represent_int)
-
-SafeRepresenter.add_representer(float,
-        SafeRepresenter.represent_float)
-
-SafeRepresenter.add_representer(list,
-        SafeRepresenter.represent_list)
-
-SafeRepresenter.add_representer(tuple,
-        SafeRepresenter.represent_list)
-
-SafeRepresenter.add_representer(dict,
-        SafeRepresenter.represent_dict)
-
-SafeRepresenter.add_representer(set,
-        SafeRepresenter.represent_set)
-
-SafeRepresenter.add_representer(datetime.date,
-        SafeRepresenter.represent_date)
-
-SafeRepresenter.add_representer(datetime.datetime,
-        SafeRepresenter.represent_datetime)
-
-SafeRepresenter.add_representer(None,
-        SafeRepresenter.represent_undefined)
-
-class Representer(SafeRepresenter):
-
-    def represent_complex(self, data):
-        if data.imag == 0.0:
-            data = '%r' % data.real
-        elif data.real == 0.0:
-            data = '%rj' % data.imag
-        elif data.imag > 0:
-            data = '%r+%rj' % (data.real, data.imag)
-        else:
-            data = '%r%rj' % (data.real, data.imag)
-        return self.represent_scalar('tag:yaml.org,2002:python/complex', data)
-
-    def represent_tuple(self, data):
-        return self.represent_sequence('tag:yaml.org,2002:python/tuple', data)
-
-    def represent_name(self, data):
-        name = '%s.%s' % (data.__module__, data.__name__)
-        return self.represent_scalar('tag:yaml.org,2002:python/name:'+name, '')
-
-    def represent_module(self, data):
-        return self.represent_scalar(
-                'tag:yaml.org,2002:python/module:'+data.__name__, '')
-
-    def represent_object(self, data):
-        # We use __reduce__ API to save the data. data.__reduce__ returns
-        # a tuple of length 2-5:
-        #   (function, args, state, listitems, dictitems)
-
-        # For reconstructing, we calls function(*args), then set its state,
-        # listitems, and dictitems if they are not None.
-
-        # A special case is when function.__name__ == '__newobj__'. In this
-        # case we create the object with args[0].__new__(*args).
-
-        # Another special case is when __reduce__ returns a string - we don't
-        # support it.
-
-        # We produce a !!python/object, !!python/object/new or
-        # !!python/object/apply node.
-
-        cls = type(data)
-        if cls in copyreg.dispatch_table:
-            reduce = copyreg.dispatch_table[cls](data)
-        elif hasattr(data, '__reduce_ex__'):
-            reduce = data.__reduce_ex__(2)
-        elif hasattr(data, '__reduce__'):
-            reduce = data.__reduce__()
-        else:
-            raise RepresenterError("cannot represent an object", data)
-        reduce = (list(reduce)+[None]*5)[:5]
-        function, args, state, listitems, dictitems = reduce
-        args = list(args)
-        if state is None:
-            state = {}
-        if listitems is not None:
-            listitems = list(listitems)
-        if dictitems is not None:
-            dictitems = dict(dictitems)
-        if function.__name__ == '__newobj__':
-            function = args[0]
-            args = args[1:]
-            tag = 'tag:yaml.org,2002:python/object/new:'
-            newobj = True
-        else:
-            tag = 'tag:yaml.org,2002:python/object/apply:'
-            newobj = False
-        function_name = '%s.%s' % (function.__module__, function.__name__)
-        if not args and not listitems and not dictitems \
-                and isinstance(state, dict) and newobj:
-            return self.represent_mapping(
-                    'tag:yaml.org,2002:python/object:'+function_name, state)
-        if not listitems and not dictitems  \
-                and isinstance(state, dict) and not state:
-            return self.represent_sequence(tag+function_name, args)
-        value = {}
-        if args:
-            value['args'] = args
-        if state or not isinstance(state, dict):
-            value['state'] = state
-        if listitems:
-            value['listitems'] = listitems
-        if dictitems:
-            value['dictitems'] = dictitems
-        return self.represent_mapping(tag+function_name, value)
-
-    def represent_ordered_dict(self, data):
-        # Provide uniform representation across different Python versions.
-        data_type = type(data)
-        tag = 'tag:yaml.org,2002:python/object/apply:%s.%s' \
-                % (data_type.__module__, data_type.__name__)
-        items = [[key, value] for key, value in data.items()]
-        return self.represent_sequence(tag, [items])
-
-Representer.add_representer(complex,
-        Representer.represent_complex)
-
-Representer.add_representer(tuple,
-        Representer.represent_tuple)
-
-Representer.add_representer(type,
-        Representer.represent_name)
-
-Representer.add_representer(collections.OrderedDict,
-        Representer.represent_ordered_dict)
-
-Representer.add_representer(types.FunctionType,
-        Representer.represent_name)
-
-Representer.add_representer(types.BuiltinFunctionType,
-        Representer.represent_name)
-
-Representer.add_representer(types.ModuleType,
-        Representer.represent_module)
-
-Representer.add_multi_representer(object,
-        Representer.represent_object)
-
diff --git a/third_party/python/PyYAML/lib3/yaml/resolver.py b/third_party/python/PyYAML/lib3/yaml/resolver.py
deleted file mode 100644
index 013896d2f1..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/resolver.py
+++ /dev/null
@@ -1,227 +0,0 @@
-
-__all__ = ['BaseResolver', 'Resolver']
-
-from .error import *
-from .nodes import *
-
-import re
-
-class ResolverError(YAMLError):
-    pass
-
-class BaseResolver:
-
-    DEFAULT_SCALAR_TAG = 'tag:yaml.org,2002:str'
-    DEFAULT_SEQUENCE_TAG = 'tag:yaml.org,2002:seq'
-    DEFAULT_MAPPING_TAG = 'tag:yaml.org,2002:map'
-
-    yaml_implicit_resolvers = {}
-    yaml_path_resolvers = {}
-
-    def __init__(self):
-        self.resolver_exact_paths = []
-        self.resolver_prefix_paths = []
-
-    @classmethod
-    def add_implicit_resolver(cls, tag, regexp, first):
-        if not 'yaml_implicit_resolvers' in cls.__dict__:
-            implicit_resolvers = {}
-            for key in cls.yaml_implicit_resolvers:
-                implicit_resolvers[key] = cls.yaml_implicit_resolvers[key][:]
-            cls.yaml_implicit_resolvers = implicit_resolvers
-        if first is None:
-            first = [None]
-        for ch in first:
-            cls.yaml_implicit_resolvers.setdefault(ch, []).append((tag, regexp))
-
-    @classmethod
-    def add_path_resolver(cls, tag, path, kind=None):
-        # Note: `add_path_resolver` is experimental.  The API could be changed.
-        # `new_path` is a pattern that is matched against the path from the
-        # root to the node that is being considered.  `node_path` elements are
-        # tuples `(node_check, index_check)`.  `node_check` is a node class:
-        # `ScalarNode`, `SequenceNode`, `MappingNode` or `None`.  `None`
-        # matches any kind of a node.  `index_check` could be `None`, a boolean
-        # value, a string value, or a number.  `None` and `False` match against
-        # any _value_ of sequence and mapping nodes.  `True` matches against
-        # any _key_ of a mapping node.  A string `index_check` matches against
-        # a mapping value that corresponds to a scalar key which content is
-        # equal to the `index_check` value.  An integer `index_check` matches
-        # against a sequence value with the index equal to `index_check`.
-        if not 'yaml_path_resolvers' in cls.__dict__:
-            cls.yaml_path_resolvers = cls.yaml_path_resolvers.copy()
-        new_path = []
-        for element in path:
-            if isinstance(element, (list, tuple)):
-                if len(element) == 2:
-                    node_check, index_check = element
-                elif len(element) == 1:
-                    node_check = element[0]
-                    index_check = True
-                else:
-                    raise ResolverError("Invalid path element: %s" % element)
-            else:
-                node_check = None
-                index_check = element
-            if node_check is str:
-                node_check = ScalarNode
-            elif node_check is list:
-                node_check = SequenceNode
-            elif node_check is dict:
-                node_check = MappingNode
-            elif node_check not in [ScalarNode, SequenceNode, MappingNode]  \
-                    and not isinstance(node_check, str) \
-                    and node_check is not None:
-                raise ResolverError("Invalid node checker: %s" % node_check)
-            if not isinstance(index_check, (str, int))  \
-                    and index_check is not None:
-                raise ResolverError("Invalid index checker: %s" % index_check)
-            new_path.append((node_check, index_check))
-        if kind is str:
-            kind = ScalarNode
-        elif kind is list:
-            kind = SequenceNode
-        elif kind is dict:
-            kind = MappingNode
-        elif kind not in [ScalarNode, SequenceNode, MappingNode]    \
-                and kind is not None:
-            raise ResolverError("Invalid node kind: %s" % kind)
-        cls.yaml_path_resolvers[tuple(new_path), kind] = tag
-
-    def descend_resolver(self, current_node, current_index):
-        if not self.yaml_path_resolvers:
-            return
-        exact_paths = {}
-        prefix_paths = []
-        if current_node:
-            depth = len(self.resolver_prefix_paths)
-            for path, kind in self.resolver_prefix_paths[-1]:
-                if self.check_resolver_prefix(depth, path, kind,
-                        current_node, current_index):
-                    if len(path) > depth:
-                        prefix_paths.append((path, kind))
-                    else:
-                        exact_paths[kind] = self.yaml_path_resolvers[path, kind]
-        else:
-            for path, kind in self.yaml_path_resolvers:
-                if not path:
-                    exact_paths[kind] = self.yaml_path_resolvers[path, kind]
-                else:
-                    prefix_paths.append((path, kind))
-        self.resolver_exact_paths.append(exact_paths)
-        self.resolver_prefix_paths.append(prefix_paths)
-
-    def ascend_resolver(self):
-        if not self.yaml_path_resolvers:
-            return
-        self.resolver_exact_paths.pop()
-        self.resolver_prefix_paths.pop()
-
-    def check_resolver_prefix(self, depth, path, kind,
-            current_node, current_index):
-        node_check, index_check = path[depth-1]
-        if isinstance(node_check, str):
-            if current_node.tag != node_check:
-                return
-        elif node_check is not None:
-            if not isinstance(current_node, node_check):
-                return
-        if index_check is True and current_index is not None:
-            return
-        if (index_check is False or index_check is None)    \
-                and current_index is None:
-            return
-        if isinstance(index_check, str):
-            if not (isinstance(current_index, ScalarNode)
-                    and index_check == current_index.value):
-                return
-        elif isinstance(index_check, int) and not isinstance(index_check, bool):
-            if index_check != current_index:
-                return
-        return True
-
-    def resolve(self, kind, value, implicit):
-        if kind is ScalarNode and implicit[0]:
-            if value == '':
-                resolvers = self.yaml_implicit_resolvers.get('', [])
-            else:
-                resolvers = self.yaml_implicit_resolvers.get(value[0], [])
-            wildcard_resolvers = self.yaml_implicit_resolvers.get(None, [])
-            for tag, regexp in resolvers + wildcard_resolvers:
-                if regexp.match(value):
-                    return tag
-            implicit = implicit[1]
-        if self.yaml_path_resolvers:
-            exact_paths = self.resolver_exact_paths[-1]
-            if kind in exact_paths:
-                return exact_paths[kind]
-            if None in exact_paths:
-                return exact_paths[None]
-        if kind is ScalarNode:
-            return self.DEFAULT_SCALAR_TAG
-        elif kind is SequenceNode:
-            return self.DEFAULT_SEQUENCE_TAG
-        elif kind is MappingNode:
-            return self.DEFAULT_MAPPING_TAG
-
-class Resolver(BaseResolver):
-    pass
-
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:bool',
-        re.compile(r'''^(?:yes|Yes|YES|no|No|NO
-                    |true|True|TRUE|false|False|FALSE
-                    |on|On|ON|off|Off|OFF)$''', re.X),
-        list('yYnNtTfFoO'))
-
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:float',
-        re.compile(r'''^(?:[-+]?(?:[0-9][0-9_]*)\.[0-9_]*(?:[eE][-+][0-9]+)?
-                    |\.[0-9_]+(?:[eE][-+][0-9]+)?
-                    |[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+\.[0-9_]*
-                    |[-+]?\.(?:inf|Inf|INF)
-                    |\.(?:nan|NaN|NAN))$''', re.X),
-        list('-+0123456789.'))
-
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:int',
-        re.compile(r'''^(?:[-+]?0b[0-1_]+
-                    |[-+]?0[0-7_]+
-                    |[-+]?(?:0|[1-9][0-9_]*)
-                    |[-+]?0x[0-9a-fA-F_]+
-                    |[-+]?[1-9][0-9_]*(?::[0-5]?[0-9])+)$''', re.X),
-        list('-+0123456789'))
-
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:merge',
-        re.compile(r'^(?:<<)$'),
-        ['<'])
-
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:null',
-        re.compile(r'''^(?: ~
-                    |null|Null|NULL
-                    | )$''', re.X),
-        ['~', 'n', 'N', ''])
-
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:timestamp',
-        re.compile(r'''^(?:[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]
-                    |[0-9][0-9][0-9][0-9] -[0-9][0-9]? -[0-9][0-9]?
-                     (?:[Tt]|[ \t]+)[0-9][0-9]?
-                     :[0-9][0-9] :[0-9][0-9] (?:\.[0-9]*)?
-                     (?:[ \t]*(?:Z|[-+][0-9][0-9]?(?::[0-9][0-9])?))?)$''', re.X),
-        list('0123456789'))
-
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:value',
-        re.compile(r'^(?:=)$'),
-        ['='])
-
-# The following resolver is only for documentation purposes. It cannot work
-# because plain scalars cannot start with '!', '&', or '*'.
-Resolver.add_implicit_resolver(
-        'tag:yaml.org,2002:yaml',
-        re.compile(r'^(?:!|&|\*)$'),
-        list('!&*'))
-
diff --git a/third_party/python/PyYAML/lib3/yaml/scanner.py b/third_party/python/PyYAML/lib3/yaml/scanner.py
deleted file mode 100644
index 7437ede1c6..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/scanner.py
+++ /dev/null
@@ -1,1435 +0,0 @@
-
-# Scanner produces tokens of the following types:
-# STREAM-START
-# STREAM-END
-# DIRECTIVE(name, value)
-# DOCUMENT-START
-# DOCUMENT-END
-# BLOCK-SEQUENCE-START
-# BLOCK-MAPPING-START
-# BLOCK-END
-# FLOW-SEQUENCE-START
-# FLOW-MAPPING-START
-# FLOW-SEQUENCE-END
-# FLOW-MAPPING-END
-# BLOCK-ENTRY
-# FLOW-ENTRY
-# KEY
-# VALUE
-# ALIAS(value)
-# ANCHOR(value)
-# TAG(value)
-# SCALAR(value, plain, style)
-#
-# Read comments in the Scanner code for more details.
-#
-
-__all__ = ['Scanner', 'ScannerError']
-
-from .error import MarkedYAMLError
-from .tokens import *
-
-class ScannerError(MarkedYAMLError):
-    pass
-
-class SimpleKey:
-    # See below simple keys treatment.
-
-    def __init__(self, token_number, required, index, line, column, mark):
-        self.token_number = token_number
-        self.required = required
-        self.index = index
-        self.line = line
-        self.column = column
-        self.mark = mark
-
-class Scanner:
-
-    def __init__(self):
-        """Initialize the scanner."""
-        # It is assumed that Scanner and Reader will have a common descendant.
-        # Reader do the dirty work of checking for BOM and converting the
-        # input data to Unicode. It also adds NUL to the end.
-        #
-        # Reader supports the following methods
-        #   self.peek(i=0)       # peek the next i-th character
-        #   self.prefix(l=1)     # peek the next l characters
-        #   self.forward(l=1)    # read the next l characters and move the pointer.
-
-        # Had we reached the end of the stream?
-        self.done = False
-
-        # The number of unclosed '{' and '['. `flow_level == 0` means block
-        # context.
-        self.flow_level = 0
-
-        # List of processed tokens that are not yet emitted.
-        self.tokens = []
-
-        # Add the STREAM-START token.
-        self.fetch_stream_start()
-
-        # Number of tokens that were emitted through the `get_token` method.
-        self.tokens_taken = 0
-
-        # The current indentation level.
-        self.indent = -1
-
-        # Past indentation levels.
-        self.indents = []
-
-        # Variables related to simple keys treatment.
-
-        # A simple key is a key that is not denoted by the '?' indicator.
-        # Example of simple keys:
-        #   ---
-        #   block simple key: value
-        #   ? not a simple key:
-        #   : { flow simple key: value }
-        # We emit the KEY token before all keys, so when we find a potential
-        # simple key, we try to locate the corresponding ':' indicator.
-        # Simple keys should be limited to a single line and 1024 characters.
-
-        # Can a simple key start at the current position? A simple key may
-        # start:
-        # - at the beginning of the line, not counting indentation spaces
-        #       (in block context),
-        # - after '{', '[', ',' (in the flow context),
-        # - after '?', ':', '-' (in the block context).
-        # In the block context, this flag also signifies if a block collection
-        # may start at the current position.
-        self.allow_simple_key = True
-
-        # Keep track of possible simple keys. This is a dictionary. The key
-        # is `flow_level`; there can be no more that one possible simple key
-        # for each level. The value is a SimpleKey record:
-        #   (token_number, required, index, line, column, mark)
-        # A simple key may start with ALIAS, ANCHOR, TAG, SCALAR(flow),
-        # '[', or '{' tokens.
-        self.possible_simple_keys = {}
-
-    # Public methods.
-
-    def check_token(self, *choices):
-        # Check if the next token is one of the given types.
-        while self.need_more_tokens():
-            self.fetch_more_tokens()
-        if self.tokens:
-            if not choices:
-                return True
-            for choice in choices:
-                if isinstance(self.tokens[0], choice):
-                    return True
-        return False
-
-    def peek_token(self):
-        # Return the next token, but do not delete if from the queue.
-        # Return None if no more tokens.
-        while self.need_more_tokens():
-            self.fetch_more_tokens()
-        if self.tokens:
-            return self.tokens[0]
-        else:
-            return None
-
-    def get_token(self):
-        # Return the next token.
-        while self.need_more_tokens():
-            self.fetch_more_tokens()
-        if self.tokens:
-            self.tokens_taken += 1
-            return self.tokens.pop(0)
-
-    # Private methods.
-
-    def need_more_tokens(self):
-        if self.done:
-            return False
-        if not self.tokens:
-            return True
-        # The current token may be a potential simple key, so we
-        # need to look further.
-        self.stale_possible_simple_keys()
-        if self.next_possible_simple_key() == self.tokens_taken:
-            return True
-
-    def fetch_more_tokens(self):
-
-        # Eat whitespaces and comments until we reach the next token.
-        self.scan_to_next_token()
-
-        # Remove obsolete possible simple keys.
-        self.stale_possible_simple_keys()
-
-        # Compare the current indentation and column. It may add some tokens
-        # and decrease the current indentation level.
-        self.unwind_indent(self.column)
-
-        # Peek the next character.
-        ch = self.peek()
-
-        # Is it the end of stream?
-        if ch == '\0':
-            return self.fetch_stream_end()
-
-        # Is it a directive?
-        if ch == '%' and self.check_directive():
-            return self.fetch_directive()
-
-        # Is it the document start?
-        if ch == '-' and self.check_document_start():
-            return self.fetch_document_start()
-
-        # Is it the document end?
-        if ch == '.' and self.check_document_end():
-            return self.fetch_document_end()
-
-        # TODO: support for BOM within a stream.
-        #if ch == '\uFEFF':
-        #    return self.fetch_bom()    <-- issue BOMToken
-
-        # Note: the order of the following checks is NOT significant.
-
-        # Is it the flow sequence start indicator?
-        if ch == '[':
-            return self.fetch_flow_sequence_start()
-
-        # Is it the flow mapping start indicator?
-        if ch == '{':
-            return self.fetch_flow_mapping_start()
-
-        # Is it the flow sequence end indicator?
-        if ch == ']':
-            return self.fetch_flow_sequence_end()
-
-        # Is it the flow mapping end indicator?
-        if ch == '}':
-            return self.fetch_flow_mapping_end()
-
-        # Is it the flow entry indicator?
-        if ch == ',':
-            return self.fetch_flow_entry()
-
-        # Is it the block entry indicator?
-        if ch == '-' and self.check_block_entry():
-            return self.fetch_block_entry()
-
-        # Is it the key indicator?
-        if ch == '?' and self.check_key():
-            return self.fetch_key()
-
-        # Is it the value indicator?
-        if ch == ':' and self.check_value():
-            return self.fetch_value()
-
-        # Is it an alias?
-        if ch == '*':
-            return self.fetch_alias()
-
-        # Is it an anchor?
-        if ch == '&':
-            return self.fetch_anchor()
-
-        # Is it a tag?
-        if ch == '!':
-            return self.fetch_tag()
-
-        # Is it a literal scalar?
-        if ch == '|' and not self.flow_level:
-            return self.fetch_literal()
-
-        # Is it a folded scalar?
-        if ch == '>' and not self.flow_level:
-            return self.fetch_folded()
-
-        # Is it a single quoted scalar?
-        if ch == '\'':
-            return self.fetch_single()
-
-        # Is it a double quoted scalar?
-        if ch == '\"':
-            return self.fetch_double()
-
-        # It must be a plain scalar then.
-        if self.check_plain():
-            return self.fetch_plain()
-
-        # No? It's an error. Let's produce a nice error message.
-        raise ScannerError("while scanning for the next token", None,
-                "found character %r that cannot start any token" % ch,
-                self.get_mark())
-
-    # Simple keys treatment.
-
-    def next_possible_simple_key(self):
-        # Return the number of the nearest possible simple key. Actually we
-        # don't need to loop through the whole dictionary. We may replace it
-        # with the following code:
-        #   if not self.possible_simple_keys:
-        #       return None
-        #   return self.possible_simple_keys[
-        #           min(self.possible_simple_keys.keys())].token_number
-        min_token_number = None
-        for level in self.possible_simple_keys:
-            key = self.possible_simple_keys[level]
-            if min_token_number is None or key.token_number < min_token_number:
-                min_token_number = key.token_number
-        return min_token_number
-
-    def stale_possible_simple_keys(self):
-        # Remove entries that are no longer possible simple keys. According to
-        # the YAML specification, simple keys
-        # - should be limited to a single line,
-        # - should be no longer than 1024 characters.
-        # Disabling this procedure will allow simple keys of any length and
-        # height (may cause problems if indentation is broken though).
-        for level in list(self.possible_simple_keys):
-            key = self.possible_simple_keys[level]
-            if key.line != self.line  \
-                    or self.index-key.index > 1024:
-                if key.required:
-                    raise ScannerError("while scanning a simple key", key.mark,
-                            "could not find expected ':'", self.get_mark())
-                del self.possible_simple_keys[level]
-
-    def save_possible_simple_key(self):
-        # The next token may start a simple key. We check if it's possible
-        # and save its position. This function is called for
-        #   ALIAS, ANCHOR, TAG, SCALAR(flow), '[', and '{'.
-
-        # Check if a simple key is required at the current position.
-        required = not self.flow_level and self.indent == self.column
-
-        # The next token might be a simple key. Let's save it's number and
-        # position.
-        if self.allow_simple_key:
-            self.remove_possible_simple_key()
-            token_number = self.tokens_taken+len(self.tokens)
-            key = SimpleKey(token_number, required,
-                    self.index, self.line, self.column, self.get_mark())
-            self.possible_simple_keys[self.flow_level] = key
-
-    def remove_possible_simple_key(self):
-        # Remove the saved possible key position at the current flow level.
-        if self.flow_level in self.possible_simple_keys:
-            key = self.possible_simple_keys[self.flow_level]
-            
-            if key.required:
-                raise ScannerError("while scanning a simple key", key.mark,
-                        "could not find expected ':'", self.get_mark())
-
-            del self.possible_simple_keys[self.flow_level]
-
-    # Indentation functions.
-
-    def unwind_indent(self, column):
-
-        ## In flow context, tokens should respect indentation.
-        ## Actually the condition should be `self.indent >= column` according to
-        ## the spec. But this condition will prohibit intuitively correct
-        ## constructions such as
-        ## key : {
-        ## }
-        #if self.flow_level and self.indent > column:
-        #    raise ScannerError(None, None,
-        #            "invalid indentation or unclosed '[' or '{'",
-        #            self.get_mark())
-
-        # In the flow context, indentation is ignored. We make the scanner less
-        # restrictive then specification requires.
-        if self.flow_level:
-            return
-
-        # In block context, we may need to issue the BLOCK-END tokens.
-        while self.indent > column:
-            mark = self.get_mark()
-            self.indent = self.indents.pop()
-            self.tokens.append(BlockEndToken(mark, mark))
-
-    def add_indent(self, column):
-        # Check if we need to increase indentation.
-        if self.indent < column:
-            self.indents.append(self.indent)
-            self.indent = column
-            return True
-        return False
-
-    # Fetchers.
-
-    def fetch_stream_start(self):
-        # We always add STREAM-START as the first token and STREAM-END as the
-        # last token.
-
-        # Read the token.
-        mark = self.get_mark()
-        
-        # Add STREAM-START.
-        self.tokens.append(StreamStartToken(mark, mark,
-            encoding=self.encoding))
-        
-
-    def fetch_stream_end(self):
-
-        # Set the current indentation to -1.
-        self.unwind_indent(-1)
-
-        # Reset simple keys.
-        self.remove_possible_simple_key()
-        self.allow_simple_key = False
-        self.possible_simple_keys = {}
-
-        # Read the token.
-        mark = self.get_mark()
-        
-        # Add STREAM-END.
-        self.tokens.append(StreamEndToken(mark, mark))
-
-        # The steam is finished.
-        self.done = True
-
-    def fetch_directive(self):
-        
-        # Set the current indentation to -1.
-        self.unwind_indent(-1)
-
-        # Reset simple keys.
-        self.remove_possible_simple_key()
-        self.allow_simple_key = False
-
-        # Scan and add DIRECTIVE.
-        self.tokens.append(self.scan_directive())
-
-    def fetch_document_start(self):
-        self.fetch_document_indicator(DocumentStartToken)
-
-    def fetch_document_end(self):
-        self.fetch_document_indicator(DocumentEndToken)
-
-    def fetch_document_indicator(self, TokenClass):
-
-        # Set the current indentation to -1.
-        self.unwind_indent(-1)
-
-        # Reset simple keys. Note that there could not be a block collection
-        # after '---'.
-        self.remove_possible_simple_key()
-        self.allow_simple_key = False
-
-        # Add DOCUMENT-START or DOCUMENT-END.
-        start_mark = self.get_mark()
-        self.forward(3)
-        end_mark = self.get_mark()
-        self.tokens.append(TokenClass(start_mark, end_mark))
-
-    def fetch_flow_sequence_start(self):
-        self.fetch_flow_collection_start(FlowSequenceStartToken)
-
-    def fetch_flow_mapping_start(self):
-        self.fetch_flow_collection_start(FlowMappingStartToken)
-
-    def fetch_flow_collection_start(self, TokenClass):
-
-        # '[' and '{' may start a simple key.
-        self.save_possible_simple_key()
-
-        # Increase the flow level.
-        self.flow_level += 1
-
-        # Simple keys are allowed after '[' and '{'.
-        self.allow_simple_key = True
-
-        # Add FLOW-SEQUENCE-START or FLOW-MAPPING-START.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(TokenClass(start_mark, end_mark))
-
-    def fetch_flow_sequence_end(self):
-        self.fetch_flow_collection_end(FlowSequenceEndToken)
-
-    def fetch_flow_mapping_end(self):
-        self.fetch_flow_collection_end(FlowMappingEndToken)
-
-    def fetch_flow_collection_end(self, TokenClass):
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Decrease the flow level.
-        self.flow_level -= 1
-
-        # No simple keys after ']' or '}'.
-        self.allow_simple_key = False
-
-        # Add FLOW-SEQUENCE-END or FLOW-MAPPING-END.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(TokenClass(start_mark, end_mark))
-
-    def fetch_flow_entry(self):
-
-        # Simple keys are allowed after ','.
-        self.allow_simple_key = True
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Add FLOW-ENTRY.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(FlowEntryToken(start_mark, end_mark))
-
-    def fetch_block_entry(self):
-
-        # Block context needs additional checks.
-        if not self.flow_level:
-
-            # Are we allowed to start a new entry?
-            if not self.allow_simple_key:
-                raise ScannerError(None, None,
-                        "sequence entries are not allowed here",
-                        self.get_mark())
-
-            # We may need to add BLOCK-SEQUENCE-START.
-            if self.add_indent(self.column):
-                mark = self.get_mark()
-                self.tokens.append(BlockSequenceStartToken(mark, mark))
-
-        # It's an error for the block entry to occur in the flow context,
-        # but we let the parser detect this.
-        else:
-            pass
-
-        # Simple keys are allowed after '-'.
-        self.allow_simple_key = True
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Add BLOCK-ENTRY.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(BlockEntryToken(start_mark, end_mark))
-
-    def fetch_key(self):
-        
-        # Block context needs additional checks.
-        if not self.flow_level:
-
-            # Are we allowed to start a key (not necessary a simple)?
-            if not self.allow_simple_key:
-                raise ScannerError(None, None,
-                        "mapping keys are not allowed here",
-                        self.get_mark())
-
-            # We may need to add BLOCK-MAPPING-START.
-            if self.add_indent(self.column):
-                mark = self.get_mark()
-                self.tokens.append(BlockMappingStartToken(mark, mark))
-
-        # Simple keys are allowed after '?' in the block context.
-        self.allow_simple_key = not self.flow_level
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Add KEY.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(KeyToken(start_mark, end_mark))
-
-    def fetch_value(self):
-
-        # Do we determine a simple key?
-        if self.flow_level in self.possible_simple_keys:
-
-            # Add KEY.
-            key = self.possible_simple_keys[self.flow_level]
-            del self.possible_simple_keys[self.flow_level]
-            self.tokens.insert(key.token_number-self.tokens_taken,
-                    KeyToken(key.mark, key.mark))
-
-            # If this key starts a new block mapping, we need to add
-            # BLOCK-MAPPING-START.
-            if not self.flow_level:
-                if self.add_indent(key.column):
-                    self.tokens.insert(key.token_number-self.tokens_taken,
-                            BlockMappingStartToken(key.mark, key.mark))
-
-            # There cannot be two simple keys one after another.
-            self.allow_simple_key = False
-
-        # It must be a part of a complex key.
-        else:
-            
-            # Block context needs additional checks.
-            # (Do we really need them? They will be caught by the parser
-            # anyway.)
-            if not self.flow_level:
-
-                # We are allowed to start a complex value if and only if
-                # we can start a simple key.
-                if not self.allow_simple_key:
-                    raise ScannerError(None, None,
-                            "mapping values are not allowed here",
-                            self.get_mark())
-
-            # If this value starts a new block mapping, we need to add
-            # BLOCK-MAPPING-START.  It will be detected as an error later by
-            # the parser.
-            if not self.flow_level:
-                if self.add_indent(self.column):
-                    mark = self.get_mark()
-                    self.tokens.append(BlockMappingStartToken(mark, mark))
-
-            # Simple keys are allowed after ':' in the block context.
-            self.allow_simple_key = not self.flow_level
-
-            # Reset possible simple key on the current level.
-            self.remove_possible_simple_key()
-
-        # Add VALUE.
-        start_mark = self.get_mark()
-        self.forward()
-        end_mark = self.get_mark()
-        self.tokens.append(ValueToken(start_mark, end_mark))
-
-    def fetch_alias(self):
-
-        # ALIAS could be a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after ALIAS.
-        self.allow_simple_key = False
-
-        # Scan and add ALIAS.
-        self.tokens.append(self.scan_anchor(AliasToken))
-
-    def fetch_anchor(self):
-
-        # ANCHOR could start a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after ANCHOR.
-        self.allow_simple_key = False
-
-        # Scan and add ANCHOR.
-        self.tokens.append(self.scan_anchor(AnchorToken))
-
-    def fetch_tag(self):
-
-        # TAG could start a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after TAG.
-        self.allow_simple_key = False
-
-        # Scan and add TAG.
-        self.tokens.append(self.scan_tag())
-
-    def fetch_literal(self):
-        self.fetch_block_scalar(style='|')
-
-    def fetch_folded(self):
-        self.fetch_block_scalar(style='>')
-
-    def fetch_block_scalar(self, style):
-
-        # A simple key may follow a block scalar.
-        self.allow_simple_key = True
-
-        # Reset possible simple key on the current level.
-        self.remove_possible_simple_key()
-
-        # Scan and add SCALAR.
-        self.tokens.append(self.scan_block_scalar(style))
-
-    def fetch_single(self):
-        self.fetch_flow_scalar(style='\'')
-
-    def fetch_double(self):
-        self.fetch_flow_scalar(style='"')
-
-    def fetch_flow_scalar(self, style):
-
-        # A flow scalar could be a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after flow scalars.
-        self.allow_simple_key = False
-
-        # Scan and add SCALAR.
-        self.tokens.append(self.scan_flow_scalar(style))
-
-    def fetch_plain(self):
-
-        # A plain scalar could be a simple key.
-        self.save_possible_simple_key()
-
-        # No simple keys after plain scalars. But note that `scan_plain` will
-        # change this flag if the scan is finished at the beginning of the
-        # line.
-        self.allow_simple_key = False
-
-        # Scan and add SCALAR. May change `allow_simple_key`.
-        self.tokens.append(self.scan_plain())
-
-    # Checkers.
-
-    def check_directive(self):
-
-        # DIRECTIVE:        ^ '%' ...
-        # The '%' indicator is already checked.
-        if self.column == 0:
-            return True
-
-    def check_document_start(self):
-
-        # DOCUMENT-START:   ^ '---' (' '|'\n')
-        if self.column == 0:
-            if self.prefix(3) == '---'  \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                return True
-
-    def check_document_end(self):
-
-        # DOCUMENT-END:     ^ '...' (' '|'\n')
-        if self.column == 0:
-            if self.prefix(3) == '...'  \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                return True
-
-    def check_block_entry(self):
-
-        # BLOCK-ENTRY:      '-' (' '|'\n')
-        return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
-
-    def check_key(self):
-
-        # KEY(flow context):    '?'
-        if self.flow_level:
-            return True
-
-        # KEY(block context):   '?' (' '|'\n')
-        else:
-            return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
-
-    def check_value(self):
-
-        # VALUE(flow context):  ':'
-        if self.flow_level:
-            return True
-
-        # VALUE(block context): ':' (' '|'\n')
-        else:
-            return self.peek(1) in '\0 \t\r\n\x85\u2028\u2029'
-
-    def check_plain(self):
-
-        # A plain scalar may start with any non-space character except:
-        #   '-', '?', ':', ',', '[', ']', '{', '}',
-        #   '#', '&', '*', '!', '|', '>', '\'', '\"',
-        #   '%', '@', '`'.
-        #
-        # It may also start with
-        #   '-', '?', ':'
-        # if it is followed by a non-space character.
-        #
-        # Note that we limit the last rule to the block context (except the
-        # '-' character) because we want the flow context to be space
-        # independent.
-        ch = self.peek()
-        return ch not in '\0 \t\r\n\x85\u2028\u2029-?:,[]{}#&*!|>\'\"%@`'  \
-                or (self.peek(1) not in '\0 \t\r\n\x85\u2028\u2029'
-                        and (ch == '-' or (not self.flow_level and ch in '?:')))
-
-    # Scanners.
-
-    def scan_to_next_token(self):
-        # We ignore spaces, line breaks and comments.
-        # If we find a line break in the block context, we set the flag
-        # `allow_simple_key` on.
-        # The byte order mark is stripped if it's the first character in the
-        # stream. We do not yet support BOM inside the stream as the
-        # specification requires. Any such mark will be considered as a part
-        # of the document.
-        #
-        # TODO: We need to make tab handling rules more sane. A good rule is
-        #   Tabs cannot precede tokens
-        #   BLOCK-SEQUENCE-START, BLOCK-MAPPING-START, BLOCK-END,
-        #   KEY(block), VALUE(block), BLOCK-ENTRY
-        # So the checking code is
-        #   if <TAB>:
-        #       self.allow_simple_keys = False
-        # We also need to add the check for `allow_simple_keys == True` to
-        # `unwind_indent` before issuing BLOCK-END.
-        # Scanners for block, flow, and plain scalars need to be modified.
-
-        if self.index == 0 and self.peek() == '\uFEFF':
-            self.forward()
-        found = False
-        while not found:
-            while self.peek() == ' ':
-                self.forward()
-            if self.peek() == '#':
-                while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                    self.forward()
-            if self.scan_line_break():
-                if not self.flow_level:
-                    self.allow_simple_key = True
-            else:
-                found = True
-
-    def scan_directive(self):
-        # See the specification for details.
-        start_mark = self.get_mark()
-        self.forward()
-        name = self.scan_directive_name(start_mark)
-        value = None
-        if name == 'YAML':
-            value = self.scan_yaml_directive_value(start_mark)
-            end_mark = self.get_mark()
-        elif name == 'TAG':
-            value = self.scan_tag_directive_value(start_mark)
-            end_mark = self.get_mark()
-        else:
-            end_mark = self.get_mark()
-            while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                self.forward()
-        self.scan_directive_ignored_line(start_mark)
-        return DirectiveToken(name, value, start_mark, end_mark)
-
-    def scan_directive_name(self, start_mark):
-        # See the specification for details.
-        length = 0
-        ch = self.peek(length)
-        while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                or ch in '-_':
-            length += 1
-            ch = self.peek(length)
-        if not length:
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        value = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        return value
-
-    def scan_yaml_directive_value(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        major = self.scan_yaml_directive_number(start_mark)
-        if self.peek() != '.':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a digit or '.', but found %r" % self.peek(),
-                    self.get_mark())
-        self.forward()
-        minor = self.scan_yaml_directive_number(start_mark)
-        if self.peek() not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a digit or ' ', but found %r" % self.peek(),
-                    self.get_mark())
-        return (major, minor)
-
-    def scan_yaml_directive_number(self, start_mark):
-        # See the specification for details.
-        ch = self.peek()
-        if not ('0' <= ch <= '9'):
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a digit, but found %r" % ch, self.get_mark())
-        length = 0
-        while '0' <= self.peek(length) <= '9':
-            length += 1
-        value = int(self.prefix(length))
-        self.forward(length)
-        return value
-
-    def scan_tag_directive_value(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        handle = self.scan_tag_directive_handle(start_mark)
-        while self.peek() == ' ':
-            self.forward()
-        prefix = self.scan_tag_directive_prefix(start_mark)
-        return (handle, prefix)
-
-    def scan_tag_directive_handle(self, start_mark):
-        # See the specification for details.
-        value = self.scan_tag_handle('directive', start_mark)
-        ch = self.peek()
-        if ch != ' ':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected ' ', but found %r" % ch, self.get_mark())
-        return value
-
-    def scan_tag_directive_prefix(self, start_mark):
-        # See the specification for details.
-        value = self.scan_tag_uri('directive', start_mark)
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected ' ', but found %r" % ch, self.get_mark())
-        return value
-
-    def scan_directive_ignored_line(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        if self.peek() == '#':
-            while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                self.forward()
-        ch = self.peek()
-        if ch not in '\0\r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a directive", start_mark,
-                    "expected a comment or a line break, but found %r"
-                        % ch, self.get_mark())
-        self.scan_line_break()
-
-    def scan_anchor(self, TokenClass):
-        # The specification does not restrict characters for anchors and
-        # aliases. This may lead to problems, for instance, the document:
-        #   [ *alias, value ]
-        # can be interpreted in two ways, as
-        #   [ "value" ]
-        # and
-        #   [ *alias , "value" ]
-        # Therefore we restrict aliases to numbers and ASCII letters.
-        start_mark = self.get_mark()
-        indicator = self.peek()
-        if indicator == '*':
-            name = 'alias'
-        else:
-            name = 'anchor'
-        self.forward()
-        length = 0
-        ch = self.peek(length)
-        while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                or ch in '-_':
-            length += 1
-            ch = self.peek(length)
-        if not length:
-            raise ScannerError("while scanning an %s" % name, start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        value = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch not in '\0 \t\r\n\x85\u2028\u2029?:,]}%@`':
-            raise ScannerError("while scanning an %s" % name, start_mark,
-                    "expected alphabetic or numeric character, but found %r"
-                    % ch, self.get_mark())
-        end_mark = self.get_mark()
-        return TokenClass(value, start_mark, end_mark)
-
-    def scan_tag(self):
-        # See the specification for details.
-        start_mark = self.get_mark()
-        ch = self.peek(1)
-        if ch == '<':
-            handle = None
-            self.forward(2)
-            suffix = self.scan_tag_uri('tag', start_mark)
-            if self.peek() != '>':
-                raise ScannerError("while parsing a tag", start_mark,
-                        "expected '>', but found %r" % self.peek(),
-                        self.get_mark())
-            self.forward()
-        elif ch in '\0 \t\r\n\x85\u2028\u2029':
-            handle = None
-            suffix = '!'
-            self.forward()
-        else:
-            length = 1
-            use_handle = False
-            while ch not in '\0 \r\n\x85\u2028\u2029':
-                if ch == '!':
-                    use_handle = True
-                    break
-                length += 1
-                ch = self.peek(length)
-            handle = '!'
-            if use_handle:
-                handle = self.scan_tag_handle('tag', start_mark)
-            else:
-                handle = '!'
-                self.forward()
-            suffix = self.scan_tag_uri('tag', start_mark)
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a tag", start_mark,
-                    "expected ' ', but found %r" % ch, self.get_mark())
-        value = (handle, suffix)
-        end_mark = self.get_mark()
-        return TagToken(value, start_mark, end_mark)
-
-    def scan_block_scalar(self, style):
-        # See the specification for details.
-
-        if style == '>':
-            folded = True
-        else:
-            folded = False
-
-        chunks = []
-        start_mark = self.get_mark()
-
-        # Scan the header.
-        self.forward()
-        chomping, increment = self.scan_block_scalar_indicators(start_mark)
-        self.scan_block_scalar_ignored_line(start_mark)
-
-        # Determine the indentation level and go to the first non-empty line.
-        min_indent = self.indent+1
-        if min_indent < 1:
-            min_indent = 1
-        if increment is None:
-            breaks, max_indent, end_mark = self.scan_block_scalar_indentation()
-            indent = max(min_indent, max_indent)
-        else:
-            indent = min_indent+increment-1
-            breaks, end_mark = self.scan_block_scalar_breaks(indent)
-        line_break = ''
-
-        # Scan the inner part of the block scalar.
-        while self.column == indent and self.peek() != '\0':
-            chunks.extend(breaks)
-            leading_non_space = self.peek() not in ' \t'
-            length = 0
-            while self.peek(length) not in '\0\r\n\x85\u2028\u2029':
-                length += 1
-            chunks.append(self.prefix(length))
-            self.forward(length)
-            line_break = self.scan_line_break()
-            breaks, end_mark = self.scan_block_scalar_breaks(indent)
-            if self.column == indent and self.peek() != '\0':
-
-                # Unfortunately, folding rules are ambiguous.
-                #
-                # This is the folding according to the specification:
-                
-                if folded and line_break == '\n'    \
-                        and leading_non_space and self.peek() not in ' \t':
-                    if not breaks:
-                        chunks.append(' ')
-                else:
-                    chunks.append(line_break)
-                
-                # This is Clark Evans's interpretation (also in the spec
-                # examples):
-                #
-                #if folded and line_break == '\n':
-                #    if not breaks:
-                #        if self.peek() not in ' \t':
-                #            chunks.append(' ')
-                #        else:
-                #            chunks.append(line_break)
-                #else:
-                #    chunks.append(line_break)
-            else:
-                break
-
-        # Chomp the tail.
-        if chomping is not False:
-            chunks.append(line_break)
-        if chomping is True:
-            chunks.extend(breaks)
-
-        # We are done.
-        return ScalarToken(''.join(chunks), False, start_mark, end_mark,
-                style)
-
-    def scan_block_scalar_indicators(self, start_mark):
-        # See the specification for details.
-        chomping = None
-        increment = None
-        ch = self.peek()
-        if ch in '+-':
-            if ch == '+':
-                chomping = True
-            else:
-                chomping = False
-            self.forward()
-            ch = self.peek()
-            if ch in '0123456789':
-                increment = int(ch)
-                if increment == 0:
-                    raise ScannerError("while scanning a block scalar", start_mark,
-                            "expected indentation indicator in the range 1-9, but found 0",
-                            self.get_mark())
-                self.forward()
-        elif ch in '0123456789':
-            increment = int(ch)
-            if increment == 0:
-                raise ScannerError("while scanning a block scalar", start_mark,
-                        "expected indentation indicator in the range 1-9, but found 0",
-                        self.get_mark())
-            self.forward()
-            ch = self.peek()
-            if ch in '+-':
-                if ch == '+':
-                    chomping = True
-                else:
-                    chomping = False
-                self.forward()
-        ch = self.peek()
-        if ch not in '\0 \r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a block scalar", start_mark,
-                    "expected chomping or indentation indicators, but found %r"
-                    % ch, self.get_mark())
-        return chomping, increment
-
-    def scan_block_scalar_ignored_line(self, start_mark):
-        # See the specification for details.
-        while self.peek() == ' ':
-            self.forward()
-        if self.peek() == '#':
-            while self.peek() not in '\0\r\n\x85\u2028\u2029':
-                self.forward()
-        ch = self.peek()
-        if ch not in '\0\r\n\x85\u2028\u2029':
-            raise ScannerError("while scanning a block scalar", start_mark,
-                    "expected a comment or a line break, but found %r" % ch,
-                    self.get_mark())
-        self.scan_line_break()
-
-    def scan_block_scalar_indentation(self):
-        # See the specification for details.
-        chunks = []
-        max_indent = 0
-        end_mark = self.get_mark()
-        while self.peek() in ' \r\n\x85\u2028\u2029':
-            if self.peek() != ' ':
-                chunks.append(self.scan_line_break())
-                end_mark = self.get_mark()
-            else:
-                self.forward()
-                if self.column > max_indent:
-                    max_indent = self.column
-        return chunks, max_indent, end_mark
-
-    def scan_block_scalar_breaks(self, indent):
-        # See the specification for details.
-        chunks = []
-        end_mark = self.get_mark()
-        while self.column < indent and self.peek() == ' ':
-            self.forward()
-        while self.peek() in '\r\n\x85\u2028\u2029':
-            chunks.append(self.scan_line_break())
-            end_mark = self.get_mark()
-            while self.column < indent and self.peek() == ' ':
-                self.forward()
-        return chunks, end_mark
-
-    def scan_flow_scalar(self, style):
-        # See the specification for details.
-        # Note that we loose indentation rules for quoted scalars. Quoted
-        # scalars don't need to adhere indentation because " and ' clearly
-        # mark the beginning and the end of them. Therefore we are less
-        # restrictive then the specification requires. We only need to check
-        # that document separators are not included in scalars.
-        if style == '"':
-            double = True
-        else:
-            double = False
-        chunks = []
-        start_mark = self.get_mark()
-        quote = self.peek()
-        self.forward()
-        chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
-        while self.peek() != quote:
-            chunks.extend(self.scan_flow_scalar_spaces(double, start_mark))
-            chunks.extend(self.scan_flow_scalar_non_spaces(double, start_mark))
-        self.forward()
-        end_mark = self.get_mark()
-        return ScalarToken(''.join(chunks), False, start_mark, end_mark,
-                style)
-
-    ESCAPE_REPLACEMENTS = {
-        '0':    '\0',
-        'a':    '\x07',
-        'b':    '\x08',
-        't':    '\x09',
-        '\t':   '\x09',
-        'n':    '\x0A',
-        'v':    '\x0B',
-        'f':    '\x0C',
-        'r':    '\x0D',
-        'e':    '\x1B',
-        ' ':    '\x20',
-        '\"':   '\"',
-        '\\':   '\\',
-        '/':    '/',
-        'N':    '\x85',
-        '_':    '\xA0',
-        'L':    '\u2028',
-        'P':    '\u2029',
-    }
-
-    ESCAPE_CODES = {
-        'x':    2,
-        'u':    4,
-        'U':    8,
-    }
-
-    def scan_flow_scalar_non_spaces(self, double, start_mark):
-        # See the specification for details.
-        chunks = []
-        while True:
-            length = 0
-            while self.peek(length) not in '\'\"\\\0 \t\r\n\x85\u2028\u2029':
-                length += 1
-            if length:
-                chunks.append(self.prefix(length))
-                self.forward(length)
-            ch = self.peek()
-            if not double and ch == '\'' and self.peek(1) == '\'':
-                chunks.append('\'')
-                self.forward(2)
-            elif (double and ch == '\'') or (not double and ch in '\"\\'):
-                chunks.append(ch)
-                self.forward()
-            elif double and ch == '\\':
-                self.forward()
-                ch = self.peek()
-                if ch in self.ESCAPE_REPLACEMENTS:
-                    chunks.append(self.ESCAPE_REPLACEMENTS[ch])
-                    self.forward()
-                elif ch in self.ESCAPE_CODES:
-                    length = self.ESCAPE_CODES[ch]
-                    self.forward()
-                    for k in range(length):
-                        if self.peek(k) not in '0123456789ABCDEFabcdef':
-                            raise ScannerError("while scanning a double-quoted scalar", start_mark,
-                                    "expected escape sequence of %d hexdecimal numbers, but found %r" %
-                                        (length, self.peek(k)), self.get_mark())
-                    code = int(self.prefix(length), 16)
-                    chunks.append(chr(code))
-                    self.forward(length)
-                elif ch in '\r\n\x85\u2028\u2029':
-                    self.scan_line_break()
-                    chunks.extend(self.scan_flow_scalar_breaks(double, start_mark))
-                else:
-                    raise ScannerError("while scanning a double-quoted scalar", start_mark,
-                            "found unknown escape character %r" % ch, self.get_mark())
-            else:
-                return chunks
-
-    def scan_flow_scalar_spaces(self, double, start_mark):
-        # See the specification for details.
-        chunks = []
-        length = 0
-        while self.peek(length) in ' \t':
-            length += 1
-        whitespaces = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch == '\0':
-            raise ScannerError("while scanning a quoted scalar", start_mark,
-                    "found unexpected end of stream", self.get_mark())
-        elif ch in '\r\n\x85\u2028\u2029':
-            line_break = self.scan_line_break()
-            breaks = self.scan_flow_scalar_breaks(double, start_mark)
-            if line_break != '\n':
-                chunks.append(line_break)
-            elif not breaks:
-                chunks.append(' ')
-            chunks.extend(breaks)
-        else:
-            chunks.append(whitespaces)
-        return chunks
-
-    def scan_flow_scalar_breaks(self, double, start_mark):
-        # See the specification for details.
-        chunks = []
-        while True:
-            # Instead of checking indentation, we check for document
-            # separators.
-            prefix = self.prefix(3)
-            if (prefix == '---' or prefix == '...')   \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                raise ScannerError("while scanning a quoted scalar", start_mark,
-                        "found unexpected document separator", self.get_mark())
-            while self.peek() in ' \t':
-                self.forward()
-            if self.peek() in '\r\n\x85\u2028\u2029':
-                chunks.append(self.scan_line_break())
-            else:
-                return chunks
-
-    def scan_plain(self):
-        # See the specification for details.
-        # We add an additional restriction for the flow context:
-        #   plain scalars in the flow context cannot contain ',' or '?'.
-        # We also keep track of the `allow_simple_key` flag here.
-        # Indentation rules are loosed for the flow context.
-        chunks = []
-        start_mark = self.get_mark()
-        end_mark = start_mark
-        indent = self.indent+1
-        # We allow zero indentation for scalars, but then we need to check for
-        # document separators at the beginning of the line.
-        #if indent == 0:
-        #    indent = 1
-        spaces = []
-        while True:
-            length = 0
-            if self.peek() == '#':
-                break
-            while True:
-                ch = self.peek(length)
-                if ch in '\0 \t\r\n\x85\u2028\u2029'    \
-                        or (ch == ':' and
-                                self.peek(length+1) in '\0 \t\r\n\x85\u2028\u2029'
-                                      + (u',[]{}' if self.flow_level else u''))\
-                        or (self.flow_level and ch in ',?[]{}'):
-                    break
-                length += 1
-            if length == 0:
-                break
-            self.allow_simple_key = False
-            chunks.extend(spaces)
-            chunks.append(self.prefix(length))
-            self.forward(length)
-            end_mark = self.get_mark()
-            spaces = self.scan_plain_spaces(indent, start_mark)
-            if not spaces or self.peek() == '#' \
-                    or (not self.flow_level and self.column < indent):
-                break
-        return ScalarToken(''.join(chunks), True, start_mark, end_mark)
-
-    def scan_plain_spaces(self, indent, start_mark):
-        # See the specification for details.
-        # The specification is really confusing about tabs in plain scalars.
-        # We just forbid them completely. Do not use tabs in YAML!
-        chunks = []
-        length = 0
-        while self.peek(length) in ' ':
-            length += 1
-        whitespaces = self.prefix(length)
-        self.forward(length)
-        ch = self.peek()
-        if ch in '\r\n\x85\u2028\u2029':
-            line_break = self.scan_line_break()
-            self.allow_simple_key = True
-            prefix = self.prefix(3)
-            if (prefix == '---' or prefix == '...')   \
-                    and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                return
-            breaks = []
-            while self.peek() in ' \r\n\x85\u2028\u2029':
-                if self.peek() == ' ':
-                    self.forward()
-                else:
-                    breaks.append(self.scan_line_break())
-                    prefix = self.prefix(3)
-                    if (prefix == '---' or prefix == '...')   \
-                            and self.peek(3) in '\0 \t\r\n\x85\u2028\u2029':
-                        return
-            if line_break != '\n':
-                chunks.append(line_break)
-            elif not breaks:
-                chunks.append(' ')
-            chunks.extend(breaks)
-        elif whitespaces:
-            chunks.append(whitespaces)
-        return chunks
-
-    def scan_tag_handle(self, name, start_mark):
-        # See the specification for details.
-        # For some strange reasons, the specification does not allow '_' in
-        # tag handles. I have allowed it anyway.
-        ch = self.peek()
-        if ch != '!':
-            raise ScannerError("while scanning a %s" % name, start_mark,
-                    "expected '!', but found %r" % ch, self.get_mark())
-        length = 1
-        ch = self.peek(length)
-        if ch != ' ':
-            while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                    or ch in '-_':
-                length += 1
-                ch = self.peek(length)
-            if ch != '!':
-                self.forward(length)
-                raise ScannerError("while scanning a %s" % name, start_mark,
-                        "expected '!', but found %r" % ch, self.get_mark())
-            length += 1
-        value = self.prefix(length)
-        self.forward(length)
-        return value
-
-    def scan_tag_uri(self, name, start_mark):
-        # See the specification for details.
-        # Note: we do not check if URI is well-formed.
-        chunks = []
-        length = 0
-        ch = self.peek(length)
-        while '0' <= ch <= '9' or 'A' <= ch <= 'Z' or 'a' <= ch <= 'z'  \
-                or ch in '-;/?:@&=+$,_.!~*\'()[]%':
-            if ch == '%':
-                chunks.append(self.prefix(length))
-                self.forward(length)
-                length = 0
-                chunks.append(self.scan_uri_escapes(name, start_mark))
-            else:
-                length += 1
-            ch = self.peek(length)
-        if length:
-            chunks.append(self.prefix(length))
-            self.forward(length)
-            length = 0
-        if not chunks:
-            raise ScannerError("while parsing a %s" % name, start_mark,
-                    "expected URI, but found %r" % ch, self.get_mark())
-        return ''.join(chunks)
-
-    def scan_uri_escapes(self, name, start_mark):
-        # See the specification for details.
-        codes = []
-        mark = self.get_mark()
-        while self.peek() == '%':
-            self.forward()
-            for k in range(2):
-                if self.peek(k) not in '0123456789ABCDEFabcdef':
-                    raise ScannerError("while scanning a %s" % name, start_mark,
-                            "expected URI escape sequence of 2 hexdecimal numbers, but found %r"
-                            % self.peek(k), self.get_mark())
-            codes.append(int(self.prefix(2), 16))
-            self.forward(2)
-        try:
-            value = bytes(codes).decode('utf-8')
-        except UnicodeDecodeError as exc:
-            raise ScannerError("while scanning a %s" % name, start_mark, str(exc), mark)
-        return value
-
-    def scan_line_break(self):
-        # Transforms:
-        #   '\r\n'      :   '\n'
-        #   '\r'        :   '\n'
-        #   '\n'        :   '\n'
-        #   '\x85'      :   '\n'
-        #   '\u2028'    :   '\u2028'
-        #   '\u2029     :   '\u2029'
-        #   default     :   ''
-        ch = self.peek()
-        if ch in '\r\n\x85':
-            if self.prefix(2) == '\r\n':
-                self.forward(2)
-            else:
-                self.forward()
-            return '\n'
-        elif ch in '\u2028\u2029':
-            self.forward()
-            return ch
-        return ''
diff --git a/third_party/python/PyYAML/lib3/yaml/serializer.py b/third_party/python/PyYAML/lib3/yaml/serializer.py
deleted file mode 100644
index fe911e67ae..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/serializer.py
+++ /dev/null
@@ -1,111 +0,0 @@
-
-__all__ = ['Serializer', 'SerializerError']
-
-from .error import YAMLError
-from .events import *
-from .nodes import *
-
-class SerializerError(YAMLError):
-    pass
-
-class Serializer:
-
-    ANCHOR_TEMPLATE = 'id%03d'
-
-    def __init__(self, encoding=None,
-            explicit_start=None, explicit_end=None, version=None, tags=None):
-        self.use_encoding = encoding
-        self.use_explicit_start = explicit_start
-        self.use_explicit_end = explicit_end
-        self.use_version = version
-        self.use_tags = tags
-        self.serialized_nodes = {}
-        self.anchors = {}
-        self.last_anchor_id = 0
-        self.closed = None
-
-    def open(self):
-        if self.closed is None:
-            self.emit(StreamStartEvent(encoding=self.use_encoding))
-            self.closed = False
-        elif self.closed:
-            raise SerializerError("serializer is closed")
-        else:
-            raise SerializerError("serializer is already opened")
-
-    def close(self):
-        if self.closed is None:
-            raise SerializerError("serializer is not opened")
-        elif not self.closed:
-            self.emit(StreamEndEvent())
-            self.closed = True
-
-    #def __del__(self):
-    #    self.close()
-
-    def serialize(self, node):
-        if self.closed is None:
-            raise SerializerError("serializer is not opened")
-        elif self.closed:
-            raise SerializerError("serializer is closed")
-        self.emit(DocumentStartEvent(explicit=self.use_explicit_start,
-            version=self.use_version, tags=self.use_tags))
-        self.anchor_node(node)
-        self.serialize_node(node, None, None)
-        self.emit(DocumentEndEvent(explicit=self.use_explicit_end))
-        self.serialized_nodes = {}
-        self.anchors = {}
-        self.last_anchor_id = 0
-
-    def anchor_node(self, node):
-        if node in self.anchors:
-            if self.anchors[node] is None:
-                self.anchors[node] = self.generate_anchor(node)
-        else:
-            self.anchors[node] = None
-            if isinstance(node, SequenceNode):
-                for item in node.value:
-                    self.anchor_node(item)
-            elif isinstance(node, MappingNode):
-                for key, value in node.value:
-                    self.anchor_node(key)
-                    self.anchor_node(value)
-
-    def generate_anchor(self, node):
-        self.last_anchor_id += 1
-        return self.ANCHOR_TEMPLATE % self.last_anchor_id
-
-    def serialize_node(self, node, parent, index):
-        alias = self.anchors[node]
-        if node in self.serialized_nodes:
-            self.emit(AliasEvent(alias))
-        else:
-            self.serialized_nodes[node] = True
-            self.descend_resolver(parent, index)
-            if isinstance(node, ScalarNode):
-                detected_tag = self.resolve(ScalarNode, node.value, (True, False))
-                default_tag = self.resolve(ScalarNode, node.value, (False, True))
-                implicit = (node.tag == detected_tag), (node.tag == default_tag)
-                self.emit(ScalarEvent(alias, node.tag, implicit, node.value,
-                    style=node.style))
-            elif isinstance(node, SequenceNode):
-                implicit = (node.tag
-                            == self.resolve(SequenceNode, node.value, True))
-                self.emit(SequenceStartEvent(alias, node.tag, implicit,
-                    flow_style=node.flow_style))
-                index = 0
-                for item in node.value:
-                    self.serialize_node(item, node, index)
-                    index += 1
-                self.emit(SequenceEndEvent())
-            elif isinstance(node, MappingNode):
-                implicit = (node.tag
-                            == self.resolve(MappingNode, node.value, True))
-                self.emit(MappingStartEvent(alias, node.tag, implicit,
-                    flow_style=node.flow_style))
-                for key, value in node.value:
-                    self.serialize_node(key, node, None)
-                    self.serialize_node(value, node, key)
-                self.emit(MappingEndEvent())
-            self.ascend_resolver()
-
diff --git a/third_party/python/PyYAML/lib3/yaml/tokens.py b/third_party/python/PyYAML/lib3/yaml/tokens.py
deleted file mode 100644
index 4d0b48a394..0000000000
--- a/third_party/python/PyYAML/lib3/yaml/tokens.py
+++ /dev/null
@@ -1,104 +0,0 @@
-
-class Token(object):
-    def __init__(self, start_mark, end_mark):
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-    def __repr__(self):
-        attributes = [key for key in self.__dict__
-                if not key.endswith('_mark')]
-        attributes.sort()
-        arguments = ', '.join(['%s=%r' % (key, getattr(self, key))
-                for key in attributes])
-        return '%s(%s)' % (self.__class__.__name__, arguments)
-
-#class BOMToken(Token):
-#    id = '<byte order mark>'
-
-class DirectiveToken(Token):
-    id = '<directive>'
-    def __init__(self, name, value, start_mark, end_mark):
-        self.name = name
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-
-class DocumentStartToken(Token):
-    id = '<document start>'
-
-class DocumentEndToken(Token):
-    id = '<document end>'
-
-class StreamStartToken(Token):
-    id = '<stream start>'
-    def __init__(self, start_mark=None, end_mark=None,
-            encoding=None):
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.encoding = encoding
-
-class StreamEndToken(Token):
-    id = '<stream end>'
-
-class BlockSequenceStartToken(Token):
-    id = '<block sequence start>'
-
-class BlockMappingStartToken(Token):
-    id = '<block mapping start>'
-
-class BlockEndToken(Token):
-    id = '<block end>'
-
-class FlowSequenceStartToken(Token):
-    id = '['
-
-class FlowMappingStartToken(Token):
-    id = '{'
-
-class FlowSequenceEndToken(Token):
-    id = ']'
-
-class FlowMappingEndToken(Token):
-    id = '}'
-
-class KeyToken(Token):
-    id = '?'
-
-class ValueToken(Token):
-    id = ':'
-
-class BlockEntryToken(Token):
-    id = '-'
-
-class FlowEntryToken(Token):
-    id = ','
-
-class AliasToken(Token):
-    id = '<alias>'
-    def __init__(self, value, start_mark, end_mark):
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-
-class AnchorToken(Token):
-    id = '<anchor>'
-    def __init__(self, value, start_mark, end_mark):
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-
-class TagToken(Token):
-    id = '<tag>'
-    def __init__(self, value, start_mark, end_mark):
-        self.value = value
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-
-class ScalarToken(Token):
-    id = '<scalar>'
-    def __init__(self, value, plain, start_mark, end_mark, style=None):
-        self.value = value
-        self.plain = plain
-        self.start_mark = start_mark
-        self.end_mark = end_mark
-        self.style = style
-