private void OnTriggerEnter(Collider other)
    {
        var ball = other.GetComponent <Ball>();

        if (ball != null)
        {
            BallInDrain?.Invoke(ball);
        }
    }
    void OnTriggerEnter(Collider other)
    {
        var _ball = other.GetComponent <Ball>();

        BallInDrain?.Invoke(_ball);
    }