static Set<S> allFieldsAbove(O o, C baseClass) {
  new TreeSet<S> fields;
  Class _c = _getClass(o);
  while (_c != null && _c != baseClass) {
    for (Field f : _c.getDeclaredFields())
      fields.add(f.getName());
    _c = _c.getSuperclass();
  }
  return fields;
}