static L<PTElement> ai_extractEntities_v1(S input) {
  if (startsWith(input, "!")) ret emptyList(); // skip commands
  input = ai_lookupCurlyCheatSheet(input);
  ret ai_extractEntities_v1(ai_parseToCulledTree(input));
}

static L<PTElement> ai_extractEntities_v1(PTElement tree) {
  new HashSet<PTElement> toSkip;
  new L<PTElement> out;
  for (PTElement e : ai_scanParseTreeForCategory(tree, "<noun>")) {
    if (toSkip.contains(e)) continue;
    //print("Entity found: " + e.text());
    out.add(e);
    PTElement ee = ai_parseTree_simplifyNode(e);
    if (ee != null && ee != e)
      toSkip.add(ee);
  }
  ret out;
}