Create a public class CountLinkedList that extends SimpleLinkedList. Provide an instance method countEqual that accepts an Object as a parameter and returns how many values in the list are equal to the passed value as an int. If the passed Object is null, throw an IllegalArgumentException.

As a reminder, our SimpleLinkedList is composed of a chain of Items, where Item is defined as an inner class on SimpleLinkedList:

The SimpleLinkedList class also has a start instance variable that refers to the start of the list, or null if the list is empty. Note that the list that you are extending does not have a size field or a get method, meaning that you will need to walk the list to solve this problem. (That's the point!)

Note that the SimpleLinkedList variable start and the Item variables value and next are set up so that you can access them directly, without using the normal settings and getters.