drawPingPongStack() {
        for(let i = 0; i < this.stacks.pingPong.length; i++) {
            const plane = this.stacks.pingPong[i];
            // be sure the plane exists
            if(plane) {
                // draw the plane
                plane._startDrawing();
            }
        }
    }
Loop through the special ping pong planes stack and draw its planes
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