private void TurnLight(bool on)
    {
        if (!on)
        {
            if (!this.GetComponent <Light>())
            {
                return;
            }
        }
        if (on)
        {
            if (this.GetComponent <Light>())
            {
                return;
            }
        }

        if (on)
        {
            BallManager.AddBallLight(this);
        }
        else
        {
            Destroy(this.GetComponent <Light>());
        }
    }