Rename .py to .pyi.

2.7/_struct.pyi

@@ -0,0 +1,29 @@
+"""Stub file for the '_struct' 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 _clearcache() -> None: ...
+
+def calcsize(*args, **kwargs) -> int: ...
+
+def pack(*args, **kwargs) -> str:
+    raise TypeError()
+
+def pack_into(*args, **kwargs) -> None:
+    raise TypeError()
+
+def unpack(*args, **kwargs) -> tuple: ...
+
+def unpack_from(*args, **kwargs) -> tuple:
+    raise TypeError()
+
+
+class Struct(object):
+    def __sizeof__() -> long: ...
+    def pack(*args, **kwargs) -> str: ...
+    def pack_into(*args, **kwargs) -> None: ...
+    def unpack(a) -> tuple: ...
+    def unpack_from(*args, **kwargs) -> tuple: ...