anchor.diff:  Since we use two-way binding, the `hero.name` and the `hero.birthday` subproperty values are automatically displayed in the corresponding elements, and when the user edits these values in the elements, the subproperties of `hero` property are updated automatically.
   
   [IMPORTANT]
  -.Use ngIf when loading content
  +.Use ngIf When Loading Content
   ====
   The hero object is retrived asynchronously after the component initialization. At this time when the retrieval starts, the component template is already rendered, but the `hero` is not loaded yet, so we can not use `hero.name` and `hero.birthday` subproperties. Using them at this moment would result in errors.
   
  
positive.code: 
  The second route path features `:id` parameter. It is received inside `HeroDetailComponent` and used there to retrive the hero object, as described above in this step.
  
  === Navigation from list to detail
  
  The last feature to implement in this step is navigation from the heroes list to the hero detail by clicking a row. Open `app/heroes.component.ts` and change it to contain the following code:
  
  
negative.code: See http://w3c.github.io/webcomponents/spec/imports/#fetching-import[Fetching Import section of the HTML Imports Spec] for more detailed information about the fetching algorithm.
  ====
  
  == Building the Application Layout with Paper Elements
  
  After the previous step we have some Polymer elements imported in `index.html` of our application. In this step we are going to use them to create an application layout with a toolbar in `AppComponent`.
  
  === Updating SystemJS Configuration
  
  For using Polymer elements in our Angular components we need to import `PolymerElement` directives from `@vaadin/angular2-polymer`. Thus we need to make the module loader (SystemJS, in our case) aware of how to load the `@vaadin/angular2-polymer` package.
  
  