{"ast_node_type":"variable","tokens":[{"end":86,"kind":"keyword","start":0,"text":"let"}]}
                let impl_trait_id = self.db.lookup_intern_impl_trait_id((*id).into());
            TyKind::OpaqueType(id, subst) => {
                let subst = subst.clone().try_fold_with(self.as_dyn(), outer_binder)?;