src/tutorial.rs: Display ping events
//!
//! block_on(future::poll_fn(move |cx| loop {
//! match swarm.poll_next_unpin(cx) {
-//! Poll::Ready(Some(event)) => {
-//! if let SwarmEvent::NewListenAddr { address, .. }= event {
-//! println!("Listening on {:?}", address);
-//! }
+//! Poll::Ready(Some(event)) => match event {
+//! SwarmEvent::NewListenAddr { address, .. } => println!("Listening on {:?}", address),
+//! SwarmEvent::Behaviour(event) => println!("{:?}", event),
+//! _ => {}
//! },
//! Poll::Ready(None) => return Poll::Ready(()),
//! Poll::Pending => return Poll::Pending
