code: func (c *wsClient) QueueNotification(marshalledJSON []byte) error {
  	// Don't queue the message if disconnected.
  	if c.Disconnected() {
  		return ErrClientQuit
  	}
  
  	c.ntfnChan <- marshalledJSON
  	return nil
  }
docs: // QueueNotification queues the passed notification to be sent to the websocket
  // client.  This function, as the name implies, is only intended for
  // notifications since it has additional logic to prevent other subsystems, such
  // as the memory pool and block manager, from blocking even when the send
  // channel is full.
  //
  // If the client is in the process of shutting down, this function returns
  // ErrClientQuit.  This is intended to be checked by long-running notification
  // handlers to stop processing if there is no more work needed to be done.