3.1 Write a method to be included in an unsorted doubly linked list class, called deleteLast, that will delete the last node in the list.

3.2 Write a method, to be included in a sorted doubly linked list class, called printBoth, that will first print the list from smallest to largest, and then print it from largest to smallest.

3.3 Write a method, to be included in an unsorted doubly linked list class, called insert_end, that will receive parameter, and it will insert it at the end of the list.