public static void test(Node node) {
    
        HashMap<Integer, Boolean> map = new HashMap<Integer, Boolean>();
        Node last = null;
        while (node != null) {
            if (map.containsKey(node.value)) {
                last.next = node.next;
                
            } else {
                map.put(node.value, true);
                
                last = node;
            }
            node = node.next;
        }
        
    }