Consider this variation on the DoublyLinkedList implementation from clas public class DoublyLinkedList private Node head, tail; private static class Node [ public Node prev, next; public String data; public Node(Node prev, String data, Node next) i this.prev - prev; this.next-next; this.data -data public DoublyLinkedListO head - tail - null; * Add data to the end (tail) of the DoublyLinkedList public void add(String data) f if (tailnull) head tail new Node(null, data, null) else t assert(tail.nextnull); tail.next new NodeCtail, data, null); tail tail.next; k a * Retrieve an element from the middle of the list * @param i Zero-based index of the element to retrieve @return The element (TBD: what to do if i is invalid) public String get(int i) Node current head for (int j-0 j