{"ast_node_type":"function","tokens":[{"end":65,"kind":"keyword","start":0,"text":"pub"}]}
    pub fn trait_of_assoc(self, def_id: DefId) -> Option<DefId> {
    /// returns the `DefId` of the trait; otherwise, returns `None`.
        self.assoc_parent(def_id).filter(|id| self.def_kind(id) == DefKind::Trait)