{"ast_node_type":"other","tokens":[{"end":79,"kind":"keyword","start":0,"text":"//"}]}
            // #2 is the `?` Kleene op, which does not take a separator (error)
        Ok(Err(token)) => match parse_kleene_op(iter, token.span) {
            Ok(Ok((KleeneOp::ZeroOrOne, span))) => {