In the sections that are commented, it says "define and create rectangle button", where in fact it's creating circles.

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 // Define and create rectangle button
 buttoncolor = color(204);
 highlight = color(153);
 circle2 = new CircleButton(130, 110, 24, buttoncolor, highlight);

 // Define and create rectangle button
 buttoncolor = color(153);
 highlight = color(102);
 circle3 = new CircleButton(130, 140, 24, buttoncolor, highlight);