Just need help detailing the box and arrow diagrams for the lines labeled a,b,c, and d. Please explain as much as you can thanks! :)

public class Node \{ Integer element; Node next; public Node(Integer e) \{ element = e; next = null; \} Suppose we run the following code... IntSinglyLinkedList s= new IntSinglyLinkedList (); s.addFirst(12); ... which produces this box-and-arrow diagram Show the step-by-step process of how s.addFirst(7) works. To do so, draw the boxes-and-arrow diagram after each line of addFirst runs. You must have 4 separate diagrams: a, b, c, d for the 4 lines labeled in the above code. You must include every variable (s, this, e,n ) once it is introduced