anchor.diff:        help: 'Includes sources into generated dill file. Having sources'
             ' allows to effectively use observatory to debug produced'
             ' application, produces better stack traces on exceptions.',
  -      defaultsTo: true);
  +      defaultsTo: true)
  +  ..addFlag('unsafe-package-serialization',
  +      help: 'Potentially unsafe: Does not allow for invalidating packages, '
  +          'additionally the output dill file might include more libraries than '
  +          'needed. The use case is test-runs, where invalidation is not really '
  +          'used, and where dill filesize does not matter, and the gain is '
  +          'improved speed.',
  +      defaultsTo: false,
  +      hide: true);
   
   String usage = '''
   Usage: server [options] [input.dart]
  
positive.code: 
  class FrontendCompiler implements CompilerInterface {
    FrontendCompiler(this._outputStream,
        {this.printerFactory, this.transformer}) {
      _outputStream ??= stdout;
      printerFactory ??= new BinaryPrinterFactory();
    }
  
    StringSink _outputStream;
    BinaryPrinterFactory printerFactory;
  
    CompilerOptions _compilerOptions;
    Uri _mainSource;
  
negative.code:         return "${r1.canonicalName}".compareTo("${r2.canonicalName}");
        });
      }
      if (unsafePackageSerialization == true) {
        writePackagesToSinkAndTrimComponent(component, sink);
      }
  
      printer.writeComponentFile(component);
      await sink.close();
  