docs: def _bot_identifier(self, message):
          """Return the identifier used to address this bot in this message.
          If one is not found, return None.
  
          :param message: a message dict from the slack api.
          """
  
          text = message['text']
  
          formatters = [
              lambda identifier: "%s " % identifier,
              lambda identifier: "%s:" % identifier,
          ]
          my_identifiers = [formatter(identifier) for identifier in [self.name, self.my_mention] for formatter in formatters]
  
          for identifier in my_identifiers:
              if text.startswith(identifier):
                  self.log.debug("sent to me:\n%s", pprint.pformat(message))
                  return identifier
  
          return None