Need help writing an async feature | Rust Programming Language Community | Page 1

I want to add some async features to this library https://crates.io/crates/reactivate

the goal is to make the update_async method

use reactivate::Reactive;

#[tokio::main]
async fn main() {
    let r = Reactive::new(10);
    let d = r.derive(|val| val + 5);

    let fut = r.update_async(move |_| async move {
      tokio::time::sleep(std::time::Duration::from_millis(10)).await;
      20
    });

    println!("{:?}", r); // Reactive(10)
    println!("{:?}", d); // Reactive(15)

    fut.await;

    println!("{:?}", r); // Reactive(20)
    println!("{:?}", d); // Reactive(25)
}

i have tried using tokio oneshot channel but i just can't get it to work

pub fn update_async<F, Fut>(&self, f: F) -> tokio::sync::oneshot::Receiver<()>
where
    F: FnOnce(&T) -> Fut + Send + 'static,
    Fut: std::future::Future<Output = T> + Send + 'static,
    T: PartialEq + Send + 'static,
{
    let (tx, rx) = tokio::sync::oneshot::channel();

    let fut = async move {
        let new_val = f(&self.value.lock().unwrap()).await;
        let mut guard = self.acq_val_lock();
        *guard = new_val;

        for obs in self.acq_obs_lock().iter_mut() {
            obs(&*guard);
        }

        let _ = tx.send(());
    };

    tokio::spawn(fut);
    rx
}

#Need help writing an async feature