anchor.diff:      new OptionHandler('-[chv?]+', handleShortOptions),
       new OptionHandler('--throw-on-error', (_) => throwOnError = true),
       new OptionHandler('--suppress-warnings', (_) => showWarnings = false),
  -    new OptionHandler('--output-type=dart|--output-type=js', passThrough),
  +    new OptionHandler('--output-type=dart|--output-type=js', setOutputType),
       new OptionHandler('--verbose', (_) => verbose = true),
       new OptionHandler('--library-root=.+', setLibraryRoot),
       new OptionHandler('--out=.+|-o.+', setOutput),
  
positive.code:     explicitOut = true;
      out = cwd.resolve(nativeToUriPath(extractParameter(argument)));
      sourceMapOut = new Uri.fromString('$out.map');
    }
  
    handleShortOptions(String argument) {
  
negative.code:   bool explicitOut = false;
    bool wantHelp = false;
    bool enableColors = false;
    String outputLanguage = 'JavaScript';
  
    passThrough(String argument) => options.add(argument);
  
  