anchor.diff:        _logging.severe('Must specify --mojo-path to mojo_run');
         return 1;
       }
  +    if (argResults['mojo-debug'] && argResults['mojo-release']) {
  +      _logging.severe('Cannot specify both --mojo-debug and --mojo-release');
  +      return 1;
  +    }
       String packageRoot = argResults['package-root'];
       ArtifactStore artifacts = new ArtifactStore(packageRoot);
       String appPath = await _makePathAbsolute(argResults['app']);
  
positive.code:     String command = await _makePathAbsolute(path.join(results['mojo-path'], 'mojo', 'devtools', 'common', 'mojo_run'));
      String appName = path.basename(appPath);
      String appDir = path.dirname(appPath);
      List<String> args = [
        '--android',
        '--release',
        'http://app/$appName',
        '--map-origin=http://app/=$appDir',
        '--map-origin=http://sky_viewer/=$skyViewerUrl',
  
negative.code:   final description = 'Run a Flutter app in mojo.';
    RunMojoCommand() {
      argParser.addFlag('android', negatable: false, help: 'Run on an Android device');
      argParser.addFlag('mojo-debug', negatable: false, help: 'Use Debug build of mojo');
      argParser.addFlag('mojo-release', negatable: false, help: 'Use Release build of mojo (default)');
  
      argParser.addOption('app', defaultsTo: 'app.flx');
      argParser.addOption('mojo-path', help: 'Path to directory containing mojo_shell and services');
      argParser.addOption('package-root', defaultsTo: 'packages');
  