{"ast_node_type":"variable","tokens":[{"end":100,"kind":"keyword","start":0,"text":"let"}]}
        let parent_def_id = tcx.hir_get_parent_item(tcx.local_def_id_to_hir_id(def_id)).to_def_id();
        // FIXME: document why/how this is different from `tcx.local_parent(def_id)`
        debug!(?parent_def_id);