{"ast_node_type":"other","tokens":[{"end":75,"kind":"keyword","start":0,"text":"with_metavar_spans(|mspans|"}]}
            with_metavar_spans(|mspans| mspans.insert(span, metavar_span));
            let span = metavar_span.with_ctxt(span.ctxt());
            TokenTree::Token(Token { kind: kind.clone(), span }, *spacing)