{"ast_node_type":"function","tokens":[{"end":67,"kind":"keyword","start":0,"text":"pub"}]}
    pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
    /// If it implements no trait, returns `None`.
        self.impl_trait_ref(def_id).map(|tr| tr.skip_binder().def_id)