code: func (c *Client) AddNodeAsync(host string, command AddNodeCommand) FutureAddNodeResult {
  	cmd := btcjson.NewAddNodeCmd(host, btcjson.AddNodeSubCmd(command))
  	return c.sendCmd(cmd)
  }
docs: // AddNodeAsync 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 AddNode for the blocking version and more details.