{"ast_node_type":"variable","tokens":[{"end":65,"kind":"keyword","start":0,"text":"let"}]}
            let open = metavar_span.with_ctxt(dspan.open.ctxt());
        TokenTree::Delimited(dspan, dspacing, delimiter, tts) => {
            let close = metavar_span.with_ctxt(dspan.close.ctxt());