static LL<BufferedImage> bufferedImageMNGrid(int cols, int rows, BufferedImage img) {
  new LL<BufferedImage> out;
  for (L<Rect> l : gridOfRects3(img.getWidth(), img.getHeight(), cols, rows))
    out.add(map(r -> clipBufferedImage(img, r), l));
  ret out;
}

static LL<BufferedImage> bufferedImageMNGrid(BufferedImage img, int cols, int rows) {
  ret bufferedImageMNGrid(cols, rows, img);
}