code: func (r *Registry) Quit(peerId enode.ID, s Stream) error {
  	peer := r.getPeer(peerId)
  	if peer == nil {
  		log.Debug("stream quit: peer not found", "peer", peerId, "stream", s)
  		// if the peer is not found, abort the request
  		return nil
  	}
  
  	msg := &QuitMsg{
  		Stream: s,
  	}
  	log.Debug("Quit ", "peer", peerId, "stream", s)
  
  	return peer.Send(context.TODO(), msg)
  }
docs: // Quit sends the QuitMsg to the peer to remove the
  // stream peer client and terminate the streaming.