{"ast_node_type":"variable","tokens":[{"end":73,"kind":"keyword","start":0,"text":"let"}]}
            let ty = tcx.at(span).type_of(def_id).instantiate_identity();
        GenericsArgsErrExtend::SelfTyAlias { def_id, span } => {
            let span_of_impl = tcx.span_of_impl(def_id);