async-tcp & future-hello: use better futures functions

future-hello-world/src/main.rs

@@ -37,4 +37,6 @@ where
 fn main() {
     let future = Display(HelloWorld);
     tokio::run(future);
+    let better_future = HelloWorld.map(|value| println!("{}", value));
+    tokio::run(better_future);
 }