Assume that you have a main() method in the client class of the SingleLinkedList class. In this main() method, there is a variable numberList of type SingleLinkedList. numberList references a single linked list of Integer objects. The number of items in this list varies (0, 1, 2, ). Write a code fragment in this main(). Your code fragment sums up all integer values in this single linked list. Hints: Your code is outside the class SingleLinkedList and DOES NOT have direct access to the data fields in this SingleLinkedList.