Imagine an everyday process, such as shutting down a computer. Programmatically, shutting down a computer involves saving the state of programs, and then, terminating the running threads and many other internal operations. Now, if the user were to see the complex steps that go behind something as simple as $$shutting down$,$ they would clearly be taken aback! Thus, in order to make life simple for the user, you can create a simple interface between the computer and the user. This would enable the user to perform the $$shut down$$ operation in a simple way. Which design pattern do you think would be useful for creating such an interface?