Macro hello_egui_utils::asyncify

macro_rules! asyncify {
    (
        $(#[$docs:meta])*
        $name:ident,
        $callback_name:ident: (impl FnMut($callback_type:ty, $($closure_arg_name:ident: $closure_arg:ty,)*) $($bounds:tt)*),
        call_prefix: ($($call_prefix:tt)*),
        generics: ($($gen:tt)*),
        async_generics: ($($async_gen:tt)*),
        parameters: ($($arg:ident: $typ:ty,)*),
        future: $future:ty,
        return_type: ($($return_type:tt)*),
        body: |($($callback_body_self:tt)*)| $body:block,
    ) => { ... };
    (
        $(#[$docs:meta])*
        $name:ident,
        $callback_name:ident: (impl FnOnce($callback_type:ty) $($bounds:tt)*),
        call_prefix: ($($call_prefix:tt)*),
        generics: ($($gen:tt)*),
        async_generics: ($($async_gen:tt)*),
        parameters: ($($arg:ident: $typ:ty,)*),
        future: $future:ty,
        return_type: ($($return_type:tt)*),
        body: |($($callback_body_self:tt)*)| $body:block,
    ) => { ... };
}

This macro generates a callback based and a async version of the function