static BufferedImage mergeRGBImagesAndRects(L<? extends RGBImageAndRect> l) {
  new L<BufferedImage> images;
  for (RGBImageAndRect i : l) {
    BufferedImage img2 = toBufferedImage(i.image);
    drawRect(img2, i.rect, Color.white);
    images.add(img2);
  }
  ret mergeBufferedImagesVertically(images);
}