anchor.diff:      outputDirectory.delete(recursive: true);
     }
   }
  +
  +Future<void> main(List<String> arguments) async {
  +  var parser = ArgParser();
  +  parser.addFlag("verbose", abbr: "v", help: "print additional information");
  +  parser.addFlag("write", abbr: "w", help: "write output to input file");
  +  parser.addOption("enable-experiment",
  +      help: "Enable one or more experimental features", allowMultiple: true);
  +
  +  var results = parser.parse(arguments);
  +  if (results.rest.isEmpty) {
  +    print("Usage: convert_multi_test.dart [-v] [-w] <input files>");
  +    print(parser.getUsage());
  +    exitCode = 1;
  +    return;
  +  }
  +  var verbose = results["verbose"] as bool;
  +  var filePaths =
  +      results.rest.map((path) => Uri.base.resolve(path).toFilePath());
  +  var writeToFile = results["write"] as bool;
  +  for (var testFilePath in filePaths) {
  +    await convertFile(testFilePath, writeToFile, verbose,
  +        (results["enable-experiment"] as List).cast<String>());
  +  }
  +}
  
positive.code:   }
  }
  
  Future<void> main(List<String> arguments) async {
    var parser = ArgParser();
    parser.addFlag("verbose", abbr: "v", help: "print additional information");
    parser.addFlag("write", abbr: "w", help: "write output to input file");
    var results = parser.parse(arguments);
    if (results.rest.length != 1) {
      print("Usage: convert_multi_test.dart [-v] [-w] <input file>");
      exitCode = 1;
      return;
    }
    var verbose = results["verbose"] as bool;
    var testFilePath = Uri.base.resolve(results.rest.single).toFilePath();
    var testFile = File(testFilePath);
    if (!await testFile.exists()) {
      print("File '${testFile.uri.toFilePath()}' not found");
  
negative.code:     // and output the result.
      var annotatedContent =
          updateErrorExpectations(contentWithoutMarkers, errors[0]);
      if (writeToFile) {
        await testFile.writeAsString(annotatedContent);
        print("Converted test '${test.path.toNativePath()}'.");
  