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: simple_0rtt_client.rs
    path of file: ./repos/phaser/phaser/vendor/rustls/examples
    
    the code of the file until where you have to start completion: use std::sync::Arc;

use std::io::{stdout, Read, Write};
use std::net::TcpStream;

use env_logger;
use rustls;
use webpki;
use webpki_roots;

fn start_session(config: &Arc<rustls::ClientConfig>, domain_name: &str) {
    let dns_name = webpki::DNSNameRef::try_from_ascii_str(domain_nam
    
fn main() {
    env_logger::init();
    let mut config = rustls::ClientConfig::new();

    // Enable early data.
    config.enable_early_data = true;
    config
        .root_store
        .add_server_trust_anchors(&webpki_roots::TLS_SERVER_ROOTS);
    let config = Arc::new(config);

    // Do two sessions. The first will be a normal request, the
    // second will use early data if the server supports it.
    start_session(&config, "mesalink.io");
    start_session(&config, "mesalink.io");
}