#[main]Expand description
Runs an async function as a synchronous entry point.
The async-rt crate selects the default executor when it re-exports
this macro. A built-in executor can be selected explicitly with, for
example, #[async_rt::main(executor = "compio")].
An explicit selection controls the runtime driving this function and the
executor used by async_rt::task.
A custom driver can be supplied with driver = expression. It drives the
annotated future without changing the executor used by async_rt::task.