Later on, when we remove nodes at the beginning or end, we'll need to account for the switch in this.head and this.tail.

Complexity for Final Solution

Since we have a reference to both head and tail nodes, the time complexities for both append and prepend are O(1) constant time complexity. Without a tail pointer, for append() we would have to iterate through the entire list in O(n) time where the list is length n. Each linked list node takes up a constant amount of space, for O(1) space complexity.