docs: def to_pandas_closed_closed(date_range, add_tz=True):
      """
      Pandas DateRange slicing is CLOSED-CLOSED inclusive at both ends.
  
      Parameters
      ----------
      date_range : `DateRange` object
          converted to CLOSED_CLOSED form for Pandas slicing
  
      add_tz : `bool`
          Adds a TimeZone to the daterange start and end if it doesn't
          have one.
  
      Returns
      -------
      Returns a date_range with start-end suitable for slicing in pandas.
      """
      if not date_range:
          return None
  
      start = date_range.start
      end = date_range.end
      if start:
          start = to_dt(start, mktz()) if add_tz else start
          if date_range.startopen:
              start += timedelta(milliseconds=1)
  
      if end:
          end = to_dt(end, mktz()) if add_tz else end
          if date_range.endopen:
              end -= timedelta(milliseconds=1)
      return DateRange(start, end)