Rename .py to .pyi.

2.7/_functools.pyi

@@ -0,0 +1,14 @@
+"""Stub file for the '_functools' module."""
+# This is an autogenerated file. It serves as a starting point
+# for a more precise manual annotation of this module.
+# Feel free to edit the source below, but remove this header when you do.
+
+from typing import List, Tuple, Dict, Undefined, GenericType
+
+def reduce(*args, **kwargs) -> object:
+    raise TypeError()
+
+
+class partial(object):
+    def __reduce__() -> tuple: ...
+    def __setstate__(a, b, c, d) -> None: ...