{"ast_node_type":"variable","tokens":[{"end":70,"kind":"keyword","start":0,"text":"let"}]}
            let parent_descr = tcx.def_descr(parent_item.to_def_id());
        let parent_info = parent_item.map(|parent_item| {
            let span = if let DefKind::Impl { .. } = tcx.def_kind(parent_item) {