constructor (private _iterableDiffers: IterableDiffers) {
    this.phrases = [];
    this.phraseClick = new EventEmitter<Phrase>();

    this.phrasesByCategory = [];

    this.m_phrasesDiffer = this._iterableDiffers.find(this.phrases).create(null);
  }

 constructor(differs: IterableDiffers) {
   this.differ = differs.find([]).create(null);
   this.comments = [];
   this.authors = ['Elliot', 'Helen', 'Jenny', 'Joe', 'Justen', 'Matt'];
   this.texts = [
     'Ours is a life of constant reruns',
     'Really cool!',
     'Thanks!'
   ];
   // setTimeout will trigger ngDoCheck
   setTimeout(() => this.addComment(), 1000);
 }

  constructor(differs: IterableDiffers) {
    this.differ = differs.find([]).create(null);
    this.comments = [];

    this.authors = ['Elliot', 'Helen', 'Jenny', 'Joe', 'Justen', 'Matt'];
    this.texts = [
      "Ours is a life of constant reruns. We're always circling back to where we'd we started, then starting all over again. Even if we don't run extra laps that day, we surely will come back for more of the same another day soon.",
      'Really cool!',
      'Thanks!'
    ];

    this.addComment();
  }

 constructor(differs: IterableDiffers) {
     this.differ = differs.find([]).create(null);
     this.comments = [];
     
     this.authors = ['Elliot', 'Helen', 'Jenny', 'Joe', 'Justen', 'Matt'];
     this.texts = [
         "I love Arsenal.", 
         "What is your name?", 
         "Awesome!"
     ];
     
     this.addComment();
 }

 ngOnChanges(changes: SimpleChanges): void {
     if ("rawItems" in changes) {
         const currentItems = changes.rawItems.currentValue;
         if (!this._differ && currentItems) {
             this._differ = this._differs.find(currentItems).create(this._items.trackBy);
         }
     }
 }

 ngOnChanges(changes: SimpleChanges): void {
   // Create a new columns differ if one does not yet exist. Initialize it based on initial value
   // of the columns property.
   const columns = changes['columns'].currentValue;
   if (!this._columnsDiffer && columns) {
     this._columnsDiffer = this._differs.find(columns).create();
     this._columnsDiffer.diff(columns);
   }
 }

 ngOnChanges(changes: SimpleChanges): void {
   // Create a new columns differ if one does not yet exist. Initialize it based on initial value
   // of the columns property or an empty array if none is provided.
   if (!this._columnsDiffer) {
     const columns = (changes['columns'] && changes['columns'].currentValue) || [];
     this._columnsDiffer = this._differs.find(columns).create();
     this._columnsDiffer.diff(columns);
   }
 }

	// called once on initial load
	@Input() set myDemo(items: string[]) {

		console.log("set myDemo called");

		this.items = items;
		items.forEach(item => {
			this.viewContainer.createEmbeddedView(this.templateRef);
		});
		this.differ = this.differs.find(items).create(this.changeDetector);
	}

 ngAfterContentInit() {
   this._dataDiffer = this._differs.find([]).create(this._tree.trackBy);
   if (!this._tree.treeControl.getChildren) {
     throw getTreeControlFunctionsMissingError();
   }
   this._tree.treeControl.getChildren(this.data).pipe(takeUntil(this._destroyed))
       .subscribe(result => {
         this._children = result;
         this.updateChildrenNodes();
       });
   this.nodeOutlet.changes.pipe(takeUntil(this._destroyed))
       .subscribe(() => this.updateChildrenNodes());
 }

 ngAfterContentInit() {
   this._dataDiffer = this._differs.find([]).create(this._tree.trackBy);
   if (!this._tree.treeControl.getChildren) {
     throw getTreeControlFunctionsMissingError();
   }
   const childrenNodes = this._tree.treeControl.getChildren(this.data);
   if (Array.isArray(childrenNodes)) {
     this.updateChildrenNodes(childrenNodes as T[]);
   } else if (childrenNodes instanceof Observable) {
     childrenNodes.pipe(takeUntil(this._destroyed))
       .subscribe(result => this.updateChildrenNodes(result));
   }
   this.nodeOutlet.changes.pipe(takeUntil(this._destroyed))
       .subscribe(() => this.updateChildrenNodes());
 }