{"ast_node_type":"function","tokens":[{"end":64,"kind":"keyword","start":0,"text":"pub"}]}
    pub fn impl_of_assoc(self, def_id: DefId) -> Option<DefId> {
    /// returns the `DefId` of the impl; otherwise returns `None`.
        self.assoc_parent(def_id).filter(|id| matches!(self.def_kind(id), DefKind::Impl { .. }))