// Start is called before the first frame update
    void Start()
    {
        Debug.Log("test start");

        SimpleArgCallback sc = new SimpleArgCallback(SimpleArgCallbackUnityFun);

        go_SetCallbackFunc(sc);

        Debug.Log(go_Add(1, 2));

        int ret = go_SendMsg("send from unity");

        Debug.Log("ret of SendMsg " + ret);
    }
 private static extern void SimpleArgCallbackFun(SimpleArgCallback c);
    private void Run2_3()
    {
        SimpleArgCallback sc = new SimpleArgCallback(SimpleArgCallbackUnityFun);

        SimpleArgCallbackFun(sc);
    }
 private static extern void go_SetCallbackFunc(SimpleArgCallback p0);