svoid gazelle22_highlightRegionOutline(int[] pixels,
  Gazelle22_ImageToRegions itr, RegionBorder_innerPoints x) {
  class X {
    bool hole;
    
    *() {
      int color = 0xFF008000, holeColor = 0xFFFFB266;
      x.onNewTrace(isHole -> hole = isHole);
      x.onFoundPoint(p ->
        pixels[p.y*itr.regions.w+p.x] = hole ? holeColor : color);
      x.run();
    }
  }
  new X;
}