pep 484: explicit reexport as intended (#4586)

See discussion on typing-sig.
This doesn't take care of some third_party libraries, will follow up on
those.

Co-authored-by: hauntsaninja <>

stdlib/2/collections.pyi

@@ -1,7 +1,7 @@
 # These are not exported.
 # These are exported.
 from typing import (
-    AbstractSet as Set,
+    AbstractSet,
     Any,
     Callable as Callable,
     Container as Container,
@@ -30,6 +30,8 @@ from typing import (
     overload,
 )
 
+Set = AbstractSet
+
 _S = TypeVar("_S")
 _T = TypeVar("_T")
 _KT = TypeVar("_KT")