code: def queue_send(self, frame, callback=None, recv_callback=None):
          
          frame = self.apply_send_hooks(frame, False)
          self.sendbuf += frame.pack()
          self.sendbuf_frames.append([frame, len(self.sendbuf), callback])
  
          if recv_callback:
              self.recv_callback = recv_callback
docs: Enqueue `frame` to the send buffer so that it is send on the next
          `do_async_send`. `callback` is an optional callable to call when the
          frame has been fully written. `recv_callback` is an optional callable
          to quickly set the `recv_callback` attribute to.