sclass CombinedStringifier<A> is IStringifier<A> {
  new CopyOnWriteArrayList<IPartialStringifier<A>> stringifiers;
  IStringifier<A> defaultStringifier = new Stringifier_ToString;
  
  public S toString(A o) {
    for (stringifier : stringifiers) {
      S s = stringifier.toStringOpt(o);
      if (s != null) ret s;
    }
    ret defaultStringifier.toString(o);
  }
}