Finish thread1

exercises/20_threads/threads1.rs

@@ -13,19 +13,22 @@
 use std::thread;
 use std::time::{Duration, Instant};
 
-fn main() {
+fn thread_func(i: u32) -> u128 {
-    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()
-        }));
+}
+
+fn main() {
+    let mut handles = vec![];
+    for i in 0..10 {
+        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?
     }