public static void main(String[] args) {
   Sequence sequence = new Sequence(10);
   for (int i = 0; i < 10; i++) sequence.add(new StringHolder(Integer.toString(i)));
   Selector selector = sequence.selector();
   while (!selector.end()) {
     System.out.print(selector.current() + " ");
     selector.next();
   }
 }