diff --git a/Lib/_abcoll.py b/Lib/_abcoll.py
index 36d39cf..4ce3df4 100644
--- a/Lib/_abcoll.py
+++ b/Lib/_abcoll.py
@@ -211,6 +211,12 @@
             return NotImplemented
         return self._from_iterable(value for value in other if value in self)
 
+    def isdisjoint(self, other):
+        for value in other:
+            if value in self:
+                return False
+        return True
+
     def __or__(self, other):
         if not isinstance(other, Iterable):
             return NotImplemented
@@ -278,6 +284,12 @@
         """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)