static BufferedImage toBufferedImageOpt(O o) {
  S c = getClassName(o);
  if (eqOneOf(c, "main$BWImage", "main$RGBImage"))
    ret (BufferedImage) call(o, "getBufferedImage");
  if (eq(c, "main$PNGFile"))
    ret (BufferedImage) call(o, "getImage");
  null;
}