Rename .py to .pyi.

2.7/_json.pyi

@@ -0,0 +1,19 @@
+"""Stub file for the '_json' 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 encode_basestring_ascii(*args, **kwargs) -> str:
+    raise TypeError()
+
+def scanstring(a, b, *args, **kwargs) -> tuple:
+    raise TypeError()
+
+
+class Encoder(object):
+    pass
+
+class Scanner(object):
+    pass