{"ast_node_type":"function","tokens":[{"end":49,"kind":"keyword","start":0,"text":"fn"}]}
    fn insert_same(&mut self, key: K, value: V) {
impl<K: Eq + Hash, V: Eq, S: BuildHasher> HashMapExt<K, V> for HashMap<K, V, S> {
        self.entry(key).and_modify(|old| assert!(*old == value)).or_insert(value);