code: def _http_date(_date_str: str) -> Optional[datetime.datetime]:
          
          if _date_str is not None:
              timetuple = parsedate(_date_str)
              if timetuple is not None:
                  return datetime.datetime(*timetuple[:6],
                                           tzinfo=datetime.timezone.utc)
          return None
docs: Process a date string, return a datetime object