refactor: rename handles

__concurrent/async_study/src/main.rs

@@ -26,7 +26,7 @@ async fn main() {
     loop_consume(left_to_right_receiver, right_consumer_stream_map.clone());
     loop_consume(right_to_left_receiver, left_consumer_stream_map.clone());
 
-    let mut joins = vec![];
+    let mut handles = vec![];
     for _ in 0..3 {
         let new_channel_id = channel_id.fetch_add(1, Ordering::SeqCst);
 
@@ -42,10 +42,10 @@ async fn main() {
         let c = loop_send(new_channel_id, right_stream_writer, format!("right sender"));
         let d = loop_send(new_channel_id, left_stream_writer, format!("left  sender"));
 
-        joins.extend([a, b, c, d]);
+        handles.extend([a, b, c, d]);
     }
-    for j in joins {
-        let _ = tokio::join!(j);
+    for h in handles {
+        let _ = tokio::join!(h);
     }
 }