let mutex_clone = mutex.clone();
        let thread = thread::spawn(move || loop {
            let state = mutex_clone.lock().unwrap().get();
            match state {
                State::Empty => thread::park(),
                State::Wait(duration) => thread::sleep(duration),
                State::Ready(data) => f(data),

        let thread = thread::spawn({
            let mutex = mutex.clone();
            move || loop {
                let state = mutex.lock().unwrap().get();
                match state {
                    State::Empty => thread::park(),
                    State::Wait(duration) => thread::sleep(duration),
                    State::Ready(data) => f(data),
                }