{"ast_node_type":"other","tokens":[{"end":93,"kind":"keyword","start":0,"text":"//"}]}
        // FIXME: within_limit should support this, instead of us having to extract the error
    ) -> Result<ExpandResult<Option<(Mark, Option<Parse<T>>)>>, UnresolvedMacro> {
        let mut unresolved_macro_err = None;