sclass ImageCategorizer {
  new L<RGBImage> images;
  float allowedDistance = 0.1f; // allowed difference within category
  
  *() {}
  *(float *allowedDistance) {}
  
  int addImage(RGBImage img) {
    for i over images:
      if (rgbDistance(images.get(i), img, allowedDistance) <= allowedDistance)
        ret i;
    images.add(img);
    ret l(images)-1;
  }
  
  int numCategories() { ret l(images); }
}