{"ast_node_type":"variable","tokens":[{"end":94,"kind":"keyword","start":0,"text":"let"}]}
            let label_span = self.mk_sp(frontmatter_opening_pos, frontmatter_opening_end_pos);
        if !last_line_trimmed.starts_with("---") {
            self.dcx().emit_err(errors::FrontmatterUnclosed {