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: websocket-server.rs
    path of file: ./repos/smol/examples
    
    the code of the file until where you have to start completion: //! A WebSocket+TLS echo server based on `async-tungstenite` and `async-native-tls`.
//!
//! First start a server:
//!
//! ```
//! cargo run --example websocket-server
//! ```
//!
//! Then start a client:
//!
//! ```
//! cargo run --example websocket-client
//! ```

use std::net::{TcpListener, TcpStream};
use std::pin::Pin;
use std::task::{Context, Poll};

use anyhow::{Context as _, Result};
use async_native_tls::{Identity, TlsAcce
    
fn main() -> Result<()> {
    // Initialize TLS with the local certificate, private key, and password.
    let identity = Identity::from_pkcs12(include_bytes!("identity.pfx"), "password")?;
    let tls = TlsAcceptor::from(native_tls::TlsAcceptor::new(identity)?);

    // Start WS and WSS servers.
    smol::block_on(async {
        let ws = listen(Async::<TcpListener>::bind(([127, 0, 0, 1], 9000))?, None);
        let wss = listen(
            Async::<TcpListener>::bind(([127, 0, 0, 1], 9001))?,
            Some(tls),
        );
        future::try_zip(ws, wss).await?;
        Ok(())
    })
}