anchor.diff:        {String formatOutput(String code),
         String generatedExtension = '.g.dart',
         List<String> additionalOutputExtensions = const [],
  -      bool isStandalone = false,
  -      String header,
  -      bool outputPartOf = true})
  +      String header})
         : _generatedExtension = generatedExtension,
           buildExtensions = {
             '.dart': [generatedExtension]..addAll(additionalOutputExtensions)
           },
  -        _isStandalone = isStandalone,
           formatOutput = formatOutput ?? _formatter.format,
  -        _header = (header ?? defaultFileHeader).trim(),
  -        _outputPartOf = outputPartOf {
  +        _header = (header ?? defaultFileHeader).trim() {
       if (_generatedExtension == null) {
         throw new ArgumentError.notNull('generatedExtension');
       }
  
positive.code:             formatOutput: formatOutput,
              generatedExtension: generatedExtension,
              additionalOutputExtensions: additionalOutputExtensions,
              isStandalone: true,
              header: header);
  }
  
  
negative.code:       contentBuffer.writeln(_header);
      }
  
      if (!_isLibraryBuilder) {
        var asset = buildStep.inputId;
        var name = nameOfPartial(library, asset);
        if (name == null) {
  