code: def __parse_direct_mention(self, message_text):
          
          matches = re.search(MENTION_REGEX, message_text)
          # the first group contains the username, the second group contains the remaining message
          return (matches.group(1), listify(matches.group(2).strip())) if matches else (None, None)
docs: Finds a direct mention (a mention that is at the beginning) in message text
              and returns the user ID which was mentioned. If there is no direct mention, returns None