code: def rank(self, item):
          '''Return the rank (index) of ``item`` in this :class:`zset`.'''
          score = self._dict.get(item)
          if score is not None:
              return self._sl.rank(scoref rank(self, item):
          '''Return the rank (index) of ``item`` in this :class:`zset`.'''
          score = self._dict.get(item)
          if score is not None:
              return self._sl.rank(score)
docs: Return the rank (index) of ``item`` in this :class:`zset`.