Well, practically it is for the caller to decide, you can `await` on a function (use it as if it were sync), or don't, grab it's `Future<something>` result and

Well, practically it is for the caller to decide, you can `await` on a function (use it as if it were sync), or don't, grab it's `Future<something>` result and work with that (async). Now `async`, you could see it as an implementation detail that you need in order to get much better performance...