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+===================
+Python Coding style
+===================
+
+Coding style
+~~~~~~~~~~~~
+
+ :ref:`black` is the tool used to reformat the Python code.
+
+Linting
+~~~~~~~
+
+The Python linting is done by :ref:`Flake8` and :ref:`pylint`
+They are executed by mozlint both at review phase and in the CI.
+
+Indentation
+~~~~~~~~~~~
+
+Four spaces in Python code.
+
+
+Makefile/moz.build practices
+----------------------------
+
+-  Changes to makefile and moz.build variables do not require
+   build-config peer review. Any other build system changes, such as
+   adding new scripts or rules, require review from the build-config
+   team.
+-  Suffix long ``if``/``endif`` conditionals with #{ & #}, so editors
+   can display matched tokens enclosing a block of statements.
+
+   ::
+
+      ifdef CHECK_TYPE #{
+        ifneq ($(flavor var_type),recursive) #{
+          $(warning var should be expandable but detected var_type=$(flavor var_type))
+        endif #}
+      endif #}
+
+-  moz.build are python and follow normal Python style.
+-  List assignments should be written with one element per line. Align
+   closing square brace with start of variable assignment. If ordering
+   is not important, variables should be in alphabetical order.
+
+   .. code-block:: python
+
+      var += [
+          'foo',
+          'bar'
+      ]
+
+-  Use ``CONFIG['CPU_ARCH'] {=arm}`` to test for generic classes of
+   architecture rather than ``CONFIG['OS_TEST'] {=armv7}`` (re: bug 886689).
+
+
+Other advices
+~~~~~~~~~~~~~
+
+-  Install the
+   `mozext <https://hg.mozilla.org/hgcustom/version-control-tools/file/default/hgext/mozext>`__
+   Mercurial extension, and address every issue reported on commit
+   or the output of ``hg critic``.
+-  Follow `PEP 8 <https://www.python.org/dev/peps/pep-0008/>`__. Please run :ref:`black` for this.
+-  Do not place statements on the same line as ``if/elif/else``
+   conditionals to form a one-liner.
+-  Global vars, please avoid them at all cost.
+-  Exclude outer parenthesis from conditionals.Use
+   ``if x > 5:,``\ rather than ``if (x > 5):``
+-  Use string formatters, rather than var + str(val).
+   ``var = 'Type %s value is %d'% ('int', 5).``
+-  Testing/Unit tests, please write them and make sure that they are executed in the CI.