anchor.diff:  
     Many of us are familiar with the component/template duality from our experience with model-view-controller (MVC) or model-view-viewmodel (MVVM). In Angular,  the component plays the part of the controller/viewmodel, and the template represents the view.
   
  -  Let’s find out what it takes to write a template for our view. We’ll cover these basic elements of template syntax:
  +  Let’s find out what it takes to write a template for our view. We’ll cover these basic elements of template syntax.
  +
  +  # Table Of Contents
   
     * [HTML](#html)
     * [Interpolation](#interpolation)
  
positive.code:   * [Local template variables](#local-vars)
    * [Input and output properties](#inputs-outputs)
    * [Template expression operators](#expression-operators)
  // #enddocregion intro
  
  :marked
    [Run the live example](/resources/live-examples/template-syntax/ts/plnkr.html)
  
  // #docregion html-1
  .l-main-section
  :marked
  
negative.code:   <a id="elvis"></a>
    ### The Elvis operator ( ?. ) and null property paths
  
    The Angular **Elvis operator (`?.`)** &mdash; perhaps better described as the "safe navigation operator" &mdash; is a fluent and convenient way to guard against null and undefined values in property paths.
    Here it is, protecting against a view render failure if the `currentHero` is null.
  // #enddocregion expression-operators-elvis-1
  +makeExample('template-syntax/ts/app/app.component.html', 'elvis-2')(format=".")
  