static Canvas showCAL(CirclesAndLines cal) {
  ret cal.show();
}

static Canvas showCAL(CirclesAndLines cal, int w, int h) {
  ret cal.show(w, h);
}

static Canvas showCAL(CirclesAndLines cal, Canvas canvas) {
  if (canvas == null) ret cal.show();
  Canvas c2 = cal.makeCanvas();
  awtReplaceComponent(canvas, c2);
  ret c2;
}

static Canvas showCAL(S calStructure) {
  ret showCAL(calFromStructure(calStructure));
}