{"ast_node_type":"variable","tokens":[{"end":77,"kind":"keyword","start":0,"text":"let"}]}
            let label_span = self.mk_sp(last_line_start_pos, whitespace_end);
                last_line_start_pos + BytePos((last_line.len() - last_line_trimmed.len()) as u32);
            self.dcx().emit_err(errors::FrontmatterInvalidClosingPrecedingWhitespace {