I saw many people's code use `async` keyword in a function without an `await` keyword in the function body. Even some official flutter example code do this. I have no idea why. What is the point? Is this a mistake or having a purpose?

Normally, I just remove the `async` keyword from those code and everything will run without any problems. Can some dart expert clarify that if there is a purpose for a function which has the `async` keyword but NO `await` keyword? Or is this just their mistake?