From bc8a08c0df96fde0f886b954eb87141ee02453c9 Mon Sep 17 00:00:00 2001
From: ocket8888 <ocket8888@apache.org>
Date: Wed, 17 Feb 2021 10:11:39 -0700
Subject: [PATCH] Add Void type

---
 Lib/typing.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Lib/typing.py b/Lib/typing.py
index 6224930c3b0275..ee13541487caa0 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -402,6 +402,24 @@ def stop() -> NoReturn:
     """
     raise TypeError(f"{self} is not subscriptable")
 
+@_SpecialForm
+def Void(self, parameters):
+    """Special type indicating functions that do not return values.
+    Example::
+
+      from typing import Void, Any
+
+      def nothing() -> Void:
+          pass
+
+      nothing() #passes type checking
+      a: Any = nothing() #fails type checking
+
+    This type is invalid in any context other than a function/method return
+    type annotation, e.g., ``List[Void]`` will fail in static type checkers.
+    """
+    raise TypeError(f"{self} is not subscriptable")
+
 @_SpecialForm
 def ClassVar(self, parameters):
     """Special type construct to mark class variables.