code: def enable_websocket(self, enable=True):
          
          if not self.websocket_enabled:
              # if the server is stopped, we want to cancel any ongoing
              # websocket tasks, to allow the server to exit promptly
              @self.listener("before_server_stop")
              def cancel_websocket_tasks(app, loop):
                  for task in self.websocket_tasks:
                      task.cancel()
  
          self.websocket_enabled = enable
docs: Enable or disable the support for websocket.
  
          Websocket is enabled automatically if websocket routes are
          added to the application.