// tok must come from htmlTok
// returns all container tags found (including content) as CNC
// honors nested tags correctly
static LL<S> findContainerTagDeep(L<S> tok, S tag) {
  new LL<S> l;
  for (int i = 1; i < l(tok); i += 2)
    if (isOpeningTag(tok.get(i), tag)) {
      int j, level = 1;
      for (j = i+2; j < tok.size(); j += 2)
        if (isOpeningTag(tok.get(j), tag))
          ++level;
        else if (isTag(tok.get(j), "/" + tag)) {
          --level;
          if (level == 0) {
            l.add(subList(tok, i-1, j+2)); // actual CNC
            break;
          }
        }
    }
  ret l;
}

static LL<S> findContainerTagDeep(S html, S tag) {
  ret findContainerTagDeep(htmlTok(html), tag);
}

Began life as a copy of #1002309