MutableSets support a remove() method.

diff --git a/Lib/_abcoll.py b/Lib/_abcoll.py
index 3a84b965b4808ab752e106446b7e54a22e58ead6..e1e65106ceaab86857492d7453bf3addacf8c439 100644 (file)
--- a/Lib/_abcoll.py
+++ b/Lib/_abcoll.py
@@ -250,6 +250,12 @@ class MutableSet(Set):
         """Return True if it was deleted, False if not there."""
         raise NotImplementedError
 
+    def remove(self, value):
+        """Remove an element. If not a member, raise a KeyError."""
+        if value not in self:
+            raise KeyError(value)
+        self.discard(value)
+
     def pop(self):
         """Return the popped value.  Raise KeyError if empty."""
         it = iter(self)