docs: def _index_range(self, version, symbol, date_range=None, **kwargs):
          """ Given a version, read the segment_index and return the chunks associated
          with the date_range. As the segment index is (id -> last datetime)
          we need to take care in choosing the correct chunks. """
          if date_range and 'segment_index' in version:
              # index is read-only but it's never written to
              index = np.frombuffer(decompress(version['segment_index']), dtype=INDEX_DTYPE)
              dtcol = self._datetime64_index(index)
              if dtcol and len(index):
                  dts = index[dtcol]
                  start, end = _start_end(date_range, dts)
                  if start > dts[-1]:
                      return -1, -1
                  idxstart = min(np.searchsorted(dts, start), len(dts) - 1)
                  idxend = min(np.searchsorted(dts, end, side='right'), len(dts) - 1)
                  return int(index['index'][idxstart]), int(index['index'][idxend] + 1)
          return super(PandasStore, self)._index_range(version, symbol, **kwargs)