code: def sort_index(self):
          sort = sorted_list_indexes(self._index)
          self._index = blist([self._index[x] for x in sort]) if self._blist else [self._index[x] for x in sort]
          for c in range(len(self._data)):
              self._data[c] = blist([self._data[c][i] for i in sort]) if self._blist else [self._data[c][i] for i in sort]