code: async def _retreive_websocket_info(self):
          
          if self._web_client is None:
              self._web_client = WebClient(
                  token=self.token,
                  base_url=self.base_url,
                  ssl=self.ssl,
                  proxy=self.proxy,
                  run_async=True,
                  loop=self._event_loop,
                  session=self._session,
              )
          self._logger.debug("Retrieving websocket info.")
          if self.connect_method in ["rtm.start", "rtm_start"]:
              resp = await self._web_client.rtm_start()
          else:
              resp = await self._web_client.rtm_connect()
          url = resp.get("url")
          if url is None:
              msg = "Unable to retreive RTM URL from Slack."
              raise client_err.SlackApiError(message=msg, response=resp)
          return url, resp.data
docs: Retreives the WebSocket info from Slack.
  
          Returns:
              A tuple of websocket information.
              e.g.
              (
                  "wss://...",
                  {
                      "self": {"id": "U01234ABC","name": "robotoverlord"},
                      "team": {
                          "domain": "exampledomain",
                          "id": "T123450FP",
                          "name": "ExampleName"
                      }
                  }
              )
  
          Raises:
              SlackApiError: Unable to retreive RTM URL from Slack.