Nobody would ever write that code in practice, for multiple reasons: - Every reference has a different explicit lifetime—one input, one output—which would rare

Nobody would ever write that code in practice, for multiple reasons: - Every reference has a different explicit lifetime—one input, one output—which would rarely ever show up in real code. - There is a tuple with 1 element, which I have never seen in the wild. - It's matching against `()`, the void type, which is never done because it's useless.