{"ast_node_type":"other","tokens":[{"end":55,"kind":"keyword","start":0,"text":"err.span_label(span,"}]}
            err.span_label(span, "unclosed delimiter");
        for &(_, span) in &self.diag_info.open_delimiters[..len] {
            self.diag_info.unmatched_delims.push(UnmatchedDelim {