code: def pop(self):
          
          if not self.items:
              raise KeyError("Set is empty")
  
          elem = self.items[-1]
          del self.items[-1]
          del self.map[elem]
          return elem
docs: Remove and return the last element from the set.
  
          Raises KeyError if the set is empty.
  
          Example:
              >>> oset = OrderedSet([1, 2, 3])
              >>> oset.pop()
              3