anchor.diff:    ElementType get type => new ElementType(_typeParameter.type, library);
   
     String toString() => element.name;
  +
  +  @override
  +  String get _href => throw 'not implemented yet';
   }
   
   class ElementType {
  
positive.code: class Dynamic extends ModelElement {
    Dynamic(DynamicElementImpl element, Library library, [String source])
        : super(element, library, source);
  }
  
  class Package {
  
negative.code:     }
      return getTypes().where(isExceptionOrError).toList();
    }
  
    @override
    String get _href => '$name/index.html';
  }
  
  class Class extends ModelElement {
  