You have been provided with a working implementation of a doubly linked list. It has an instance reference variable to the current head Node of the list and an instance reference variable to the current tail Node of the list, and uses doubly linked Nodes. The relevant part of that implementation is shown below public class DoublyLinkedList implements List The following code illustrates the use of our iterator: it declares a reference variable "iterator" of on "st" t then calls the method iteratorO on the list, and assigns the returned reference to "iterator". The iterator is then moved forward 5 imes it loops back to the front on the fourth backward 3 times (it loops back to the rear on the sccond move backward) private sttic lass Node Ilist"is a reference variable of type Lisi ". // hat contains the valuesIA, B, CI private T valuc private Node previous; private Node next; Iterator previous. Node head; private Node goes here The interface Iterator is defined as follows: public interface tcrator implements List The following code illustrates the use of our iterator: it declares a reference variable "iterator" of on "st" t then calls the method iteratorO on the list, and assigns the returned reference to "iterator". The iterator is then moved forward 5 imes it loops back to the front on the fourth backward 3 times (it loops back to the rear on the sccond move backward) private sttic lass Node Ilist"is a reference variable of type Lisi ". // hat contains the valuesIA, B, CI private T valuc private Node previous; private Node next; Iterator previous. Node head; private Node goes here The interface Iterator is defined as follows: public interface tcrator