Merge branch 'master' into refactor-hints

exercises/threads/threads1.rs

@@ -5,6 +5,8 @@
 // of "waiting..." and the program ends without timing out when running,
 // you've got it :)
 
+// I AM NOT DONE
+
 use std::sync::Arc;
 use std::thread;
 use std::time::Duration;