public void reverse() {
        Node<Data> current = head;                                              // 1
        Node<Data> previous = null;                                             // 1

        while (current != null) {                                               // 2
            Node<Data> next = current.next;                                     // 3
            current.next = previous;                                            // 4
            previous = current;                                                 // 5
            current = next;                                                     // 6
        }
        head = previous;                                                        // 7
    }