async fn main() {

    // Create a Watchable<u32> which holds a u32 and notifies watchers when the

    // contained value changes.

    let watchable = Watchable::default();

    // Create a watcher that will efficiently be able to monitor and read the

    // contained value as it is updated.

    let watcher = watchable.watch();

    // Spawn a background worker that will print out the values the watcher reads.

    let watching_task = tokio::task::spawn(watching_task(watcher));

    for i in 1_u32..=1000 {

        watchable.replace(i);

    }

    drop(watchable);

    // Wait for the spawned task to exit.

    watching_task.await.unwrap();

async fn watching_task(watcher: Watcher<u32>) {

    // A Watcher can be converted into a Stream, which allows for asynchronous

    // iteration.

    let mut stream = watcher.into_stream();

    while let Some(value) = stream.next().await {

        // The value we received will not necessarily be sequential, even though

        // the main thread is publishing a complete sequence.

        println!("Read value: {value}");

    }

}

#[test]

fn runs() {

    main()

}