{"ast_node_type":"variable","tokens":[{"end":74,"kind":"keyword","start":0,"text":"let"}]}
                let ty = Ty::new_alias(tcx, alias_ty.kind(tcx), alias_ty);
                let alias_ty = ty::AliasTy::new_from_args(tcx, def_id, args);
                Ok((ty, tcx.def_kind(def_id), def_id))