{"ast_node_type":"variable","tokens":[{"end":82,"kind":"keyword","start":0,"text":"let"}]}
                    let offset = sm.doctest_offset_line(&loc.file.name, loc.line);
                    let filename = sm.filename_for_diagnostics(&loc.file.name);
                    let message = format!("{}:{}:{}", filename, offset, loc.col.0 + 1);