code: def popitem(self):
          
          with self.__timer as time:
              self.expire(time)
              try:
                  key = next(iter(self.__links))
              except StopIteration:
                  raise KeyError('%s is empty' % self.__class__.__name__)
              else:
                  return (key, self.pop(key))
docs: Remove and return the `(key, value)` pair least recently used that
          has not already expired.