interface IG22MasksHolder<A> {

  replace Mask with IG22Mask<A>.

  WidthAndHeight maskSize();

  L<Image2B> maskImages();

  //LPair<Image2B, A> maskImagesWithLabels();

  L<? extends Mask> masks();

  G22GhostImage ghost();

  double certainty();

  default int nMasks() { ret l(masks()); }

  default S renderCountAndCertainty() {

    ret main nMasks(nMasks()) + " with c=" + formatDouble3(certainty());

  }

  default bool canSplit() { ret nMasks() > 1; }

  default L<IG22MasksHolder<A>> subHolders() { null; }

  default void transformSubHolders(IF1<IG22MasksHolder<A>> f) {}

  default PStackComputable<Void> findSimilarMasks(G22FindSimilarMasksTask<A> task) {

    ret new FindSimilarMasks_BruteForce<A>(this, task);

  }

  srecord noeq FindSimilarMasks_BruteForce<A>(IG22MasksHolder<A> masksHolder, G22FindSimilarMasksTask<A> task) extends PStackComputableWithStep<Void> {

    Mask maskBeingTested;

    toString { ret formatFunctionCall(shortClassName(this), masksHolder, "step=" + step); }

    void step(IPStack stack) {

      if (task.ended()) ret with stack.ret();

      if (step == 0) {

        ++step;

        stack.optionsOrReturn(this, map(masksHolder.masks(), mask ->

          self -> self.maskBeingTested = mask));

      } else {

        task.tryMask(maskBeingTested);

        stack.ret();

      }

    }

  }

  <B> IG22MasksHolder<B> cloneTreeWithLabelTransform(IF1<A, B> transformLabel);

  default L<A> labels() { ret map(masks(), -> .label()); }

  default Image2B regionToMaskImage(IImageRegion region) {

    ret region == null ?: g22standardRegionToMaskImage(region, maskSize());

  }

}