code: def _format_strings(self):
          
  
          values = self.values.astype(object)
          is_dates_only = _is_dates_only(values)
          formatter = (self.formatter or
                       _get_format_datetime64(is_dates_only,
                                              date_format=self.date_format))
          fmt_values = [formatter(x) for x in values]
  
          return fmt_values
docs: we by definition have a TZ