exercises 06 done, onto structs

exercises/06_move_semantics/move_semantics4.rs

@@ -1,6 +1,4 @@
-fn main() {
-    // You can optionally experiment here.
-}
+fn main() {}
 
 #[cfg(test)]
 mod tests {
@@ -10,8 +8,8 @@ mod tests {
     fn move_semantics4() {
         let mut x = Vec::new();
         let y = &mut x;
-        let z = &mut x;
         y.push(42);
+        let z = &mut x;
         z.push(13);
         assert_eq!(x, [42, 13]);
     }