code: func SendMessageCallback(command, family, flags int, cb CallbackFunc, arg interface{}) error {
  	msg, err := NewMessage(command, family, flags)
  	if err != nil {
  		return err
  	}
  	defer msg.Free()
  
  	return msg.SendCallback(cb, arg)
  }
docs: // SendMessageCallback creates and sends a netlink message. The specified
  // callback function will be called for each message that is received in
  // response.