{"ast_node_type":"other","tokens":[{"end":64,"kind":"keyword","start":0,"text":"with_metavar_spans(|mspans|"}]}
        with_metavar_spans(|mspans| mspans.insert(mk_span, sp));
        tscx.marker.mark_span(&mut sp);
        // Both the open delim and close delim get the same span, which covers the