In this project, you will implement a variation of the linked list called a circular linked list. The link field of the final node of a circular linked list is not NULL; instead, the link member of the tail pointer points back to the first node. In this project, an extra reference variable is used to refer to the beginning of the list; this variable will be NULL if the list is empty. Revise the third bag class developed in this chapter to use a circular linked-list implementation.