public static void main(String[] args) {
Sequence s = new Sequence(2);
System.out.println(s.add(new Cat()));
System.out.println(s.add(new Mouse()));
System.out.println(s.add(new Cat()));
Iterator it = s.iterator();
while (it.hasNext()) {
Rodent o = (Rodent) s.next();
o.eat();
}
}