Describe how you would swap two adjacent elements by adjusting only the links (and not the data) in a (a) singly linked lists. (b) doubly linked lists. Note: For the singly linked list you are given the reference to the head node. For the doubly linked list, you are given the reference to the head and tail node. In both case you are given the index number that you are looking for, so you will have to include the search step for finding the appropriate node reference.