code: def _reindex(self):
          
          self._len2split_idx = {}
          last_split = -1
          for split_idx, split in enumerate(self._splits):
              self._len2split_idx.update(
                  dict(list(zip(list(range(last_split + 1, split)), [split_idx] * (split - (last_split + 1))))))
docs: Index every sentence into a cluster