Update typing.py from python/typing (#2870)

Author: ilevkivskyi

lib-typing/2.7/mod_generics_cache.py

@@ -0,0 +1,14 @@
+"""Module for testing the behavior of generics across different modules."""
+
+from typing import TypeVar, Generic
+
+T = TypeVar('T')
+
+
+class A(Generic[T]):
+    pass
+
+
+class B(Generic[T]):
+    class A(Generic[T]):
+        pass