// A is the user object associated with each mask (aka a "label")
sclass G22HashedMasks<A> {
  record noeq Mask(Image2B image) is IG22Mask<A> {
    gettable new MultiSet<A> labels;
    int hash;
    
    public int hashCode() {
      if (hash == 0)
        hash = (int) hashImage2B(image);
      ret hash;
    }
    
    public Image2B image() { ret image; }
  }

  new Map<Int, Mask> masks;

  void addRegion(IImageRegion region, A label) {
    var mask = new Mask(regionToMaskImage(region));
    var existingMask = masks.get(mask.hashCode());
    if (existingMask != null)
      mask = existingMask;
    else
      masks.put(mask.hashCode(), mask);
    mask.labels.add(label);
    ghost_cache = null;
    certainty_cache = null;
    labels.add(label);
  }
  
  L<Mask> masks() { ret valuesList(masks); }
  
  !include early #1035854 // Masks holder Include
}