static Set<S> thingsOnScreenMap2_md5s;

static MultiMap<S, Rect> thingsOnScreenMap2() {
  L<RectAndMD5> segments = segmentedScreenFromCacheFile();
  if (segments == null) null;
  new MultiMap<S, Rect> map;
  SS comments = thingsOnScreenDefinitions();
  new HashSet<S> md5s;
  for (RectAndMD5 r : segments) {
    md5s.add(r.md5);
    putIfKeyNempty(map, comments.get(r.md5), r.r);
  }
  thingsOnScreenMap2_md5s = md5s;
  ret map;
}

Began life as a copy of #1010722