Merge pull request PacktPublishing#30 from PacktPublishing/issue27

fix issue PacktPublishing#27

Author: cfsamson

ch07/a-coroutine/src/main.rs

@@ -1,7 +1,6 @@
 use std::{
     thread,
-    time::Duration,
-    Instant
+    time::Duration
 };
 
 mod future;