tostr

    public static <T> String toString(Node<T> front) {
        if (front == null) {
            return "null";
        }
        Node<T> curr = front;
        java.lang.String str = "[ " + curr.nodeValue;
        while (curr.next != null) {
            curr = curr.next;
            str += "," + curr.nodeValue;
        }
        str += " ]";
        return str;
    }