sclass AnimatedImageSurface > ImageSurface {
  FlexibleRateTimer animationTimer = new(20).pileUp(false);
  
  selfType fps aka setFPS(double fps) {
    animationTimer.setFrequencyImmediately(fps);
    this;
  }
  
  swappable BufferedImage makeImage() {
    ret whiteImage(10, 10);
  }
  
  *() {}
  *(IF0<BufferedImage> *makeImage) {}
  *(double fps, IF0<BufferedImage> *makeImage) { setFPS(fps); }
}