public static void main( String [ ] args ) {
    Animal animal = new LivingAnimal();
    animal.describe();
    animal = new LegDecorator(animal);
    animal.describe();
    animal = new WingDecorator(animal);
    animal.describe();
    animal = new GrowlDecorator(animal);
    animal = new GrowlDecorator(animal);
    animal.describe();
    }