Rewrite the definition of the class template GenericList given in Display

17.4 and Display 17.6 so that it is more general. This more general version has the added feature that you can step through the items on the list in order. One item is always the current item. You can ask for the current item, change the current item to the next item, change the current item to the previous item, start at the beginning of the list by making the first item on the list the current item, and ask for the nth item on the list. To do this, you will add the following members: an additional member variable that records the position on the list of the current item, a member function that returns the current item as a value, a member function that makes the next item the current item, a member function that makes the previous item the current item, a member function that makes the first item on the list the current item, and a member function that returns the nth item on the list given n as an argument. (Number items as in arrays, so that the first item is the 0^th item, the next is item number 1, and so forth.)

Note that there are situations in which some of these function actions are

not possible. For example, an empty list has no first item, and there is no

item after the last item in any list. Be sure to test for the empty list and

handle it appropriately. Be sure to test for the beginning and end of the

list and handle these cases appropriately. Write a suitable test program to

test this class template.