More progress.

src/storage.rs

@@ -33,4 +33,8 @@ impl Storage {
     pub fn get_item(&mut self, id: usize) -> &mut Item {
         &mut self.items[id]
     }
+
+    pub fn items_mut(&mut self) -> impl Iterator<Item = &mut Item> {
+        self.items.iter_mut()
+    }
 }