(Optional) Complete the class hierarchy, which includes Link List, Queue, and Priority queue, using the online code as a basis. Complete the remaining operations in the Link List class, and call them as appropriate in the public interface of queue and Priority queue.

1. Be sure to add copy constructors for each class (or prototype them in the private access region or use =delete in the prototype to suppress copying if you truly do not want to allow copies).

2. Instantiate LinkList using either constructor, then demonstrate how each of your operations works. Be sure to invoke Print () after adding or deleting an element.

3. Instantiate queue and Priority queue, and demonstrate that each of the operations in their public interfaces works correctly. Remember to demonstrate the inherited operations in the public interface of queue for instances of Priority queue.