code: func (c *Client) NotifyReceivedAsync(addresses []btcutil.Address) FutureNotifyReceivedResult {
  	// Not supported in HTTP POST mode.
  	if c.config.HTTPPostMode {
  		return newFutureError(ErrWebsocketsRequired)
  	}
  
  	// Ignore the notification if the client is not interested in
  	// notifications.
  	if c.ntfnHandlers == nil {
  		return newNilFutureResult()
  	}
  
  	// Convert addresses to strings.
  	addrs := make([]string, 0, len(addresses))
  	for _, addr := range addresses {
  		addrs = append(addrs, addr.String())
  	}
  	cmd := btcjson.NewNotifyReceivedCmd(addrs)
  	return c.sendCmd(cmd)
  }
docs: // NotifyReceivedAsync returns an instance of a type that can be used to get the
  // result of the RPC at some future time by invoking the Receive function on
  // the returned instance.
  //
  // See NotifyReceived for the blocking version and more details.
  //
  // NOTE: This is a btcd extension and requires a websocket connection.
  //
  // NOTE: Deprecated. Use LoadTxFilterAsync instead.