1 files changed, 6 insertions, 0 deletions
diff --git a/Lib/_weakrefset.py b/Lib/_weakrefset.py
index 43f9a6e..990c3a6 100644
--- a/Lib/_weakrefset.py
+++ b/Lib/_weakrefset.py
@@ -171,6 +171,12 @@ class WeakSet(object):
             return NotImplemented
         return self.data == set(ref(item) for item in other)
 
+    def __ne__(self, other):
+        opposite = self.__eq__(other)
+        if opposite is NotImplemented:
+            return NotImplemented
+        return not opposite
+
     def symmetric_difference(self, other):
         newset = self.copy()
         newset.symmetric_difference_update(other)