static void removeFromLayers(Shape shape) {
if (!layerOf.containsKey(shape)) return;
int oldLayer = layerOf.get(shape);
layerContents.get(oldLayer).remove(shape);
if (layerContents.get(oldLayer).isEmpty()) {
layerContents.remove(oldLayer);
layers.remove((Integer) oldLayer);
}
layerOf.remove(shape);
}
static void removeCounter(Counter counter) {
counters.remove(counter);
}
