{"ast_node_type":"other","tokens":[{"end":65,"kind":"keyword","start":0,"text":"///"}]}
    /// Sets the value of the entry with the `VacantEntry`'s key,
impl<'map, A: ?Sized + Downcast, V: IntoBox<A>> VacantEntry<'map, A, V> {
    /// and returns a mutable reference to it