code: def removevalues(self, key, values):
          
          self.setlist(key, [v for v in self.getlist(key) if v not in values])
          return self
docs: Removes all <values> from the values of <key>. If <key> has no
          remaining values after removevalues(), the key is popped.
  
          Example:
            omd = omdict([(1, 1), (1, 11), (1, 1), (1, 111)])
            omd.removevalues(1, [1, 111])
            omd.allitems() == [(1, 11)]
  
          Returns: <self>.