docs: async def send(self, data, namespace=None, callback=None):
          """Send a message to the server.
  
          The only difference with the :func:`socketio.Client.send` method is
          that when the ``namespace`` argument is not given the namespace
          associated with the class is used.
  
          Note: this method is a coroutine.
          """
          return await self.client.send(data,
                                        namespace=namespace or self.namespace,
                                        callback=callback)