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: z_sub_liveliness.rs
    path of file: ./repos/zenoh/examples/examples
    
    the code of the file until where you have to start completion: //
// Copyright (c) 2023 ZettaScale Technology
//
// This program and the accompanying materials are made avai
    
async fn main() {
    // Initiate logging
    env_logger::init();

    let (config, key_expr) = parse_args();

    println!("Opening session...");
    let session = zenoh::open(config).res().await.unwrap();

    println!("Declaring Liveliness Subscriber on '{}'...", &key_expr);

    let subscriber = session
        .liveliness()
        .declare_subscriber(&key_expr)
        .res()
        .await
        .unwrap();

    println!("Enter 'q' to quit...");
    let mut stdin = async_std::io::stdin();
    let mut input = [0_u8];
    loop {
        select!(
            sample = subscriber.recv_async() => {
                let sample = sample.unwrap();
                match sample.kind {
                    SampleKind::Put => println!(
                        ">> [LivelinessSubscriber] New alive token ('{}')",
                        sample.key_expr.as_str()),
                    SampleKind::Delete => println!(
                        ">> [LivelinessSubscriber] Dropped token ('{}')",
                        sample.key_expr.as_str()),
                }
            },

            _ = stdin.read_exact(&mut input).fuse() => {
                match input[0] {
                    b'q' => break,
                    0 => sleep(Duration::from_secs(1)).await,
                    _ => (),
                }
            }
        );
    }
}