docs: def _start_end(date_range, dts):
      """
      Return tuple: [start, end] of np.datetime64 dates that are inclusive of the passed
      in datetimes.
      """
      # FIXME: timezones
      assert len(dts)
      _assert_no_timezone(date_range)
      date_range = to_pandas_closed_closed(date_range, add_tz=False)
      start = np.datetime64(date_range.start) if date_range.start else dts[0]
      end = np.datetime64(date_range.end) if date_range.end else dts[-1]
      return start, end