class Test {
  public static <A> LinkedList<A> empty () {
    return new LinkedList<A>();
  }

  public static <A> LinkedList<A> singleton (A x) {
    LinkedList<A> xs = new LinkedList<A>();
    xs.add(x);
    return xs;
  }

  public static void main (String[] args) {
    LinkedList<Byte> xs = empty();
    LinkedList<String> ys = singleton(null);
  }
}