code: func (c *Client) SendFromCommentAsync(fromAccount string,
  	toAddress btcutil.Address, amount btcutil.Amount, minConfirms int,
  	comment, commentTo string) FutureSendFromResult {
  
  	addr := toAddress.EncodeAddress()
  	cmd := btcjson.NewSendFromCmd(fromAccount, addr, amount.ToBTC(),
  		&minConfirms, &comment, &commentTo)
  	return c.sendCmd(cmd)
  }
docs: // SendFromCommentAsync 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 SendFromComment for the blocking version and more details.