types.NoneType no longer exists in python 3

diff --git a/tornado/stack_context.py b/tornado/stack_context.py
index fd3ac50e1c43ce0f4748e2de448a9a5282738538..c5570b499b77ffbc6b56979804041554f816a4da 100644 (file)
--- a/tornado/stack_context.py
+++ b/tornado/stack_context.py
@@ -48,8 +48,6 @@ Example usage:
 
 from __future__ import with_statement
 
-from types import NoneType
-
 import contextlib
 import functools
 import itertools
@@ -57,6 +55,8 @@ import logging
 import sys
 import threading
 
+NoneType = type(None)
+
 class _State(threading.local):
     def __init__(self):
         self.contexts = ()