1 files changed, 48 insertions, 0 deletions
diff --git a/third_party/python/multidict/multidict/_abc.py b/third_party/python/multidict/multidict/_abc.py
new file mode 100644
index 0000000000..0603cdd244
--- /dev/null
+++ b/third_party/python/multidict/multidict/_abc.py
@@ -0,0 +1,48 @@
+import abc
+import sys
+import types
+from collections.abc import Mapping, MutableMapping
+
+
+class _TypingMeta(abc.ABCMeta):
+    # A fake metaclass to satisfy typing deps in runtime
+    # basically MultiMapping[str] and other generic-like type instantiations
+    # are emulated.
+    # Note: real type hints are provided by __init__.pyi stub file
+    if sys.version_info >= (3, 9):
+
+        def __getitem__(self, key):
+            return types.GenericAlias(self, key)
+
+    else:
+
+        def __getitem__(self, key):
+            return self
+
+
+class MultiMapping(Mapping, metaclass=_TypingMeta):
+    @abc.abstractmethod
+    def getall(self, key, default=None):
+        raise KeyError
+
+    @abc.abstractmethod
+    def getone(self, key, default=None):
+        raise KeyError
+
+
+class MutableMultiMapping(MultiMapping, MutableMapping):
+    @abc.abstractmethod
+    def add(self, key, value):
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def extend(self, *args, **kwargs):
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def popone(self, key, default=None):
+        raise KeyError
+
+    @abc.abstractmethod
+    def popall(self, key, default=None):
+        raise KeyError