use slightly simpler enum syntax

asottile · asottile · commit 55cdfc6fd26f · 2020-11-09T12:29:57.000-08:00
diff --git a/pre_commit/envcontext.py b/pre_commit/envcontext.py
@@ -8,11 +8,7 @@
 from typing import Tuple
 from typing import Union
 
-
-class _Unset(enum.Enum):
-    UNSET = 1
-
-
+_Unset = enum.Enum('_Unset', 'UNSET')
 UNSET = _Unset.UNSET
 
 
