anchor.diff:    new File(htmlFile).writeAsStringSync(html);
   
     String dart = '''
  -import 'package:polymer/polymer.dart';
  +${importDartHtml}import 'package:polymer/polymer.dart';
   
   /**
    * A Polymer $element element.
    */
   @CustomTag('$element')
  -class $capitalizedName extends PolymerElement {
  +$classDeclaration
   
     /// Constructor used to create instance of ${capitalizedName}.
  -  ${capitalizedName}.created() : super.created() {
  +  ${capitalizedName}.created() : super.created() {$polymerCreatedString
     }
   
     /*
  
positive.code:   print('  ' + path.absolute(path.join(directory, underscoreName + '.dart')));
    print('  ' + path.absolute(path.join(directory, underscoreName + '.html')));
  }
  
negative.code:       distanceToPackageRoot--;
      }
    }
    
    var superElement = options['extends'];
    
    if ((superElement == null ) || 
        _isDOMElement(superElement) ||
        _isPolymerElement(superElement)) {
      try {
        _createBoilerPlate(element, options['extends'], outputDir, 
            distanceToPackageRoot);
      } on Exception catch(e, t) {
        print('Error creating files in $outputDir');
        print('$e $t');
        exitCode = 1;
        return;
      }
    } else {
      if (superElement.contains('-')) {
        print('Extending invalid element "$superElement". Polymer elements '
            'may contain only lowercase letters at least one hyphen.');
      } else {
        print('Extending invalid element "$superElement". $superElement is not '
            ' a builtin DOM type.');
      }
      exitCode = 1;
      return;
    }
  