the borrow checker

src/main.rs

@@ -20,5 +20,13 @@ impl List{
     pub fn new() -> Self {
         Self { head: Link::Empty }
     }
+
+    pub fn push(&mut self, elem: i32) {
+        let new_node = Node {
+            elem: elem,
+            next: self.head
+        };
+    }
+
 }