The next problem involves working with two different linked lists. You’ll need to write a function outside of the LinkedList class.

Given two sorted linked lists as input, your function should return a single sorted linked list made up of the nodes from both inputs.

# linked_list_a = a -> c -> x -> z
# linked_list_b = b -> g -> u

merge(linked_list_a, linked_list_b)
# a -> b -> c -> g -> u -> x -> z

One way to solve this problem would be reassigning .next for each node in both lists. This approach is a constant space solution because we’re combining the inputs rather than creating a new linked list. In the above example, we would start by setting 'a' node’s .next property to the 'b' node.

Another way would be to create a new linked list. In the example, the head node of our new linked list would be 'a' node.

To recap:

• write a function: merge().
• merge() takes two arguments: sorted linked lists.
• return an instance of LinkedList which contains all the nodes from both of the input lists in sorted order.