static File qoify(File imageFile) {
  if (isQOIFile(imageFile)) ret imageFile;
  loading "QOIfy" {
    BufferedImage img = loadImage2(imageFile);
    File destFile = replaceExtension(imageFile, ".qoi");
    File atticFile = newFile(javaxDataDir("QOIfied original pictures"), imageFile.getName());
    atticFile = makeFileNameUnique(atticFile);
    saveQOIVerbose(destFile, img);
    moveFileVerbose(imageFile, atticFile);
    print("Conversion done.");
    ret destFile;
  }
}

Began life as a copy of #1015317