static <A, B> LinkedHashMap<A, B> lhm_replaceFirstKey(Map<A, B> map, A newKey) {
  new LinkedHashMap<A, B> out;
  bool first = true;
  for (A a, B b : unnull(map)) {
    if (first) {
      out.put(newKey, b);
      first = false;
    } else
      out.put(a, b);
  }
  ret out;
}