A linked list class with an O(1) addLast method needs an efficient mechanism to get to the end of the list, for example by setting an instance variable to the last element. It is then possible to remove the refer ence to the first node if one makes the next reference of the last node point to the first node, so that all nodes form a cycle. Such an implementation is called a circular linked list. Turn the linked list implementation of Section 16.1.8 into a circular singly-linked list.