anchor.diff:  import 'dart:io';
   import 'dart:isolate';
   
  +import 'package:args/command_runner.dart';
   import 'package:logging/logging.dart';
   import 'package:path/path.dart' as p;
   
  
positive.code:     return;
    }
  
    var buildScript = await generateBuildScript();
    var scriptFile = new File(scriptLocation)..createSync(recursive: true);
    scriptFile.writeAsStringSync(buildScript);
  
    var exitPort = new ReceivePort();
    await Isolate.spawnUri(new Uri.file(p.absolute(scriptLocation)), args, null,
        onExit: exitPort.sendPort);
    await exitPort.first;
    await logListener.cancel();
  }
  
negative.code: import 'package:build_runner/src/logging/std_io_logging.dart';
  
  Future<Null> main(List<String> args) async {
    // Use the actual command runner to parse the args and immediately print the
    // usage information if there is no command provided or the help command was
    // explicitly invoked.
    var commandRunner = new BuildCommandRunner([])
      ..addCommand(new _GenerateBuildScript());
    var parsedArgs = commandRunner.parse(args);
    var commandName = parsedArgs.command?.name;
    if (commandName == null || commandName == 'help') {
  