Rewrite the definition of the class template Generic List 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 it