use async_recursion::async_recursion;
#[must_use]
fn fib(
n: u32,
) -> ::core::pin::Pin<
Box<dyn ::core::future::Future<Output = u64> + ::core::marker::Send>,
> {
Box::pin(async move {
match n {
0 => {
::std::rt::begin_panic("zero is not a valid argument to fib()!");
}
1 | 2 => 1,
3 => 2,
_ => fib(n - 1).await + fib(n - 2).await,
}
})
}