anchor.diff:  
   import 'package:analyzer/file_system/physical_file_system.dart';
   import 'package:analyzer_utilities/package_root.dart' as package_root;
  -import 'package:path/src/context.dart';
   
   import '../messages/error_code_documentation_info.dart';
   import '../messages/error_code_info.dart';
  
positive.code: [meta-visibleForOverriding]: https://pub.dev/documentation/meta/latest/meta/visibleForOverriding-constant.html
  [meta-visibleForTesting]: https://pub.dev/documentation/meta/latest/meta/visibleForTesting-constant.html
  ''');
      List<String> errorCodes = infoByName.keys.toList();
      errorCodes.sort();
      for (String errorCode in errorCodes) {
        DiagnosticInformation info = infoByName[errorCode]!;
        if (info.hasDocumentation) {
          sink.writeln();
          info.writeOn(sink);
  
negative.code: /// Generate the file `diagnostics.md` based on the documentation associated
  /// with the declarations of the error codes.
  void main() async {
    var sink = File(computeOutputPath()).openWrite();
    var generator = DocumentationGenerator();
    generator.writeDocumentation(sink);
    await sink.flush();
    await sink.close();
  