// initialize topology builder
let dht_builder = DhtBuilder::new(
    vec!(0, 6148914691236516864, 12297829382473033728));

// initialize swarm
let address = "127.0.0.1:12000".parse()
    .expect("parse seed addr");
let seed_address = "127.0.0.1:12010".parse()
    .expect("parse seed addr");
let (mut swarm, dht) =
    Swarm::new(0, address, Some(seed_address), dht_builder);

// set swarm instance metadata
swarm.set_metadata("rpc_addr", "127.0.0.1:12002");
swarm.set_metadata("xfer_addr", "127.0.0.1:12003");

// start swarm
swarm.start().expect("swarm start");

{
    let dht = dht.read().unwrap();
        match dht.get(0) {
            Some(node) => println!("{:?}",
                node.get_metadata("rpc_addr")),
            None => println!("node not found"),
    }
}

// stop swarm
swarm.stop().expect("swarm start");