static Map litmap(O... x) {
  new TreeMap map;
  litmap_impl(map, x);
  ret map;
}

static void litmap_impl(Map map, O... x) {
  for (int i = 0; i < x.length-1; i += 2)
    if (x[i+1] != null)
      map.put(x[i], x[i+1]);
}