You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: audio_level_observer.rs
    path of file: ./repos/mediasoup/rust/tests/integration
    
    the code of the file until where you have to start completion: use async_io::Timer;
use futures_lite::future;
use mediasoup::audio_level_observer::AudioLevelObserverOptions;
use mediasoup::prelude::*;
use mediasoup::router::RouterOptions;
use mediasoup::rtp_parameters::{MimeTypeAudio, RtpCodecCapability, RtpCodecParametersParameters};
use mediasoup::worker::{Worker, WorkerSettings};
use mediasoup::worker_manager::WorkerManager;
use std::env;
use std::num::{NonZeroU32, NonZeroU8};
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::time::Duration;

fn media_codecs() -> Vec<RtpCodecCapability> {
  
    
fn create() {
    future::block_on(async move {
        let worker = init().await;

        let router = worker
            .create_router(RouterOptions::new(media_codecs()))
            .await
            .expect("Failed to create router");

        let new_observer_count = Arc::new(AtomicUsize::new(0));

        router
            .on_new_rtp_observer({
                let new_observer_count = Arc::clone(&new_observer_count);

                move |_new_rtp_observer| {
                    new_observer_count.fetch_add(1, Ordering::SeqCst);
                }
            })
            .detach();

        let audio_level_observer = router
            .create_audio_level_observer(AudioLevelObserverOptions::default())
            .await
            .expect("Failed to create AudioLevelObserver");

        assert_eq!(new_observer_count.load(Ordering::SeqCst), 1);
        assert!(!audio_level_observer.closed());
        assert!(!audio_level_observer.paused());

        let dump = router.dump().await.expect("Failed to get router dump");

        assert_eq!(
            dump.rtp_observer_ids.into_iter().collect::<Vec<_>>(),
            vec![audio_level_observer.id()]
        );
    });
}