anchor.diff:  
     Now imagine a hosting parent component that binds to the `HeroDetailComponent`'s `deleteRequest` event.
   
  -+makeExample('template-syntax/ts/app/app.component.html',
  -'event-binding-to-component')(format=".")
  ++makeExcerpt('app/app.component.html', 'event-binding-to-component', '')
  +
   :marked
     When the `deleteRequest` event fires, Angular calls the parent component's `deleteHero` method,
     passing the *hero-to-delete* (emitted by `HeroDetail`) in the `$event` variable.
  
positive.code:   The best it can do is raise an event reporting the user's delete request.
  
    Here are the pertinent excerpts from that `HeroDetailComponent`:
  +makeExample('template-syntax/ts/app/hero-detail.component.ts',
  'template-1', 'HeroDetailComponent.ts (template)')(format=".")
  +makeExample('template-syntax/ts/app/hero-detail.component.ts',
  'deleteRequest', 'HeroDetailComponent.ts (delete logic)')(format=".")
  
  :marked
    The component defines a `deleteRequest` property that returns an `EventEmitter`.
  
negative.code:   When developing data entry forms, we often want to both display a data property and update that property when the user makes changes.
  
    Two-way data binding with the `NgModel` directive makes that easy. Here's an example:
  +makeExcerpt('app/app.component.html', 'NgModel-1', '')
  
  +ifDocsFor('ts|js')
    .callout.is-important
  