anchor.diff:  /// Use [KeyValueDiffers] and [IterableDiffers] to add your custom check
   /// mechanisms.
   ///
  -/// ## Example
  +/// ### Example
   ///
   /// In the following example `ngDoCheck` uses an [IterableDiffers] to detect the
   /// updates to the array `list`:
  
positive.code: ///   ''',
  ///   directives: const [ParentComponent, ChildComponent]
  /// )
  /// export class App {}
  ///
  /// bootstrap(App);
  /// ```
  abstract class AfterContentInit {
    ngAfterContentInit();
  
negative.code: /// )
  /// class ParentComponent implements AfterViewInit {
  ///   @ViewChild(ChildComponent)
  ///   ChildComponent viewChild;
  ///
  ///   ParentComponent() {
  ///     // viewChild is not initialized yet
  