Finish thread1

exercises/20_threads/threads1.rs

@@ -13,19 +13,22 @@
 use std::thread;
 use std::time::{Duration, Instant};
 
+fn thread_func(i: u32) -> u128 {
+    let start = Instant::now();
+    thread::sleep(Duration::from_millis(250));
+    println!("thread {} is complete", i);
+    start.elapsed().as_millis()
+}
+
 fn main() {
     let mut handles = vec![];
     for i in 0..10 {
-        handles.push(thread::spawn(move || {
-            let start = Instant::now();
-            thread::sleep(Duration::from_millis(250));
-            println!("thread {} is complete", i);
-            start.elapsed().as_millis()
-        }));
+        handles.push(thread::spawn(move || thread_func(i)));
     }
 
     let mut results: Vec<u128> = vec![];
     for handle in handles {
+        results.push(handle.join().unwrap());
         // TODO: a struct is returned from thread::spawn, can you use it?
     }