Macro async_try_get 

macro_rules! async_try_get {
    (async fn($input:ident: &mut $ity:ty) -> Result<($oty:ty, $aty:ty), $ety:ty> { $($v:tt)+ }) => { ... };
    (async fn<$a:lifetime, $b:lifetime>($input:ident: &mut $ity:ty) -> Result<($oty:ty, $aty:ty), $ety:ty> { $($v:tt)+ }) => { ... };
}

A macro for quickly implementing crate::AsyncTryGetFut without capturing.

If you need capturing, you will have to manually capture what you want in a user-defined struct and implement crate::AsyncTryGetFut for that struct.