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: main.rs
    path of file: ./repos/hermit-rs/examples/tls/src
    
    the code of the file until where you have to start completion: //! Simple HTTPS echo service based on hyper_util and rustls
//!
//! The example is derived from `<https://github.com/rustls/hyper-rustls>
    
pub async fn main() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
	env_logger::Builder::new().parse_filters("debug").init();

	// see readme of rustls-rustcrypto
	println!("USE THIS AT YOUR OWN RISK!");
	println!("See https://github.com/RustCrypto/rustls-rustcrypto for details!");

	let addr = SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), 9975);

	// Load public certificate.
	let certs = load_certs()?;
	// Load private key.
	let key = load_private_key()?;

	println!("Starting to serve on https://{}", addr);

	// Create a TCP listener via tokio.
	let incoming = TcpListener::bind(addr).await?;

	// Build TLS configuration.
	let mut server_config =
		ServerConfig::builder_with_provider(Arc::new(rustls_rustcrypto::provider()))
			.with_safe_default_protocol_versions()?
			.with_no_client_auth()
			.with_single_cert(certs, key)?;
	server_config.alpn_protocols = vec![b"h2".to_vec(), b"http/1.1".to_vec(), b"http/1.0".to_vec()];
	let tls_acceptor = TlsAcceptor::from(Arc::new(server_config));

	let service = service_fn(echo);

	loop {
		let (tcp_stream, _remote_addr) = incoming.accept().await?;

		let tls_acceptor = tls_acceptor.clone();
		tokio::spawn(async move {
			let tls_stream = match tls_acceptor.accept(tcp_stream).await {
				Ok(tls_stream) => tls_stream,
				Err(err) => {
					eprintln!("failed to perform tls handshake: {err:#}");
					return;
				}
			};
			if let Err(_err) = Builder::new(TokioExecutor::new())
				.serve_connection(TokioIo::new(tls_stream), service)
				.await
			{
				//eprintln!("failed to serve connection: {err:#}");
			}
		});
	}
}