public static void main(String[] args) {
        LinkedList<Character> s1 = new LinkedList<>();
        s1.add('1');
        s1.add('2');
        s1.add('3');
        s1.add('4');
        LinkedList<Character> s2 = new LinkedList<>();
        s2.add('a');
        s2.add('b');
        s2.add('c');
        s2.add('d');
        Iterator i1 = s1.iterator(), i2 = s2.iterator();
        LinkedList<Iterator<Character>> is = new LinkedList<>();
        is.add(i1);
        is.add(i2);
        ZigzagIterator z = new ZigzagIterator(is);
        int i = 0;
        while (z.hasNext()) {
            Printer.println(z.next());
        }
    }