def _http_date(_date_str: str) -> Optional[datetime.datetime]:
        """Process a date string, return a datetime object
        """
        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
Process a date string, return a datetime object