sS ol(S... list) {
  ret ol(asList(list));
}

sS ol(LS list, O... params) {
  new StringBuilder buf;
  int i = indexOf(params, null); // null separates params for ul from params for li
  if (i == -1) i = l(params);
  for (S s : withoutNulls(list))
    buf.append(tag("li", s, subArray(params, i+1))).append("\n");
  ret containerTag("ol", buf, subArray(params, 0, i)) + "\n";
}