anchor.diff:    The view still renders but the displayed value is blank; we see only "`The title is`" with nothing after it.
     That is reasonable behavior. At least the app doesn't crash.
   
  -  Suppose the template expression involves a property path as in this next example 
  +  Suppose the template expression involves a property path as in this next example
     where we’re displaying the `firstName` of a null hero.
   
   code-example(format="" language="html").
  
positive.code: 
    Evaluation of an Event Binding template expression may have side-effects as this one clearly does.
    They are not just OK (unlike in property bindings); they are expected.
    
    The expression could update the model thereby triggering other changes that percolate through the system, changes that
    are ultimately displayed in this view and other views.
    The event processing may result in queries and saves to a remote server. It's all good.
  
negative.code: 
      We can write our own two-way binding directive that follows this pattern if we're ever in the mood to do so.
  :marked
    Is `[(ngModel)]` all we need? Is there ever a reason to fall back to its expanded form?
  
    Well `NgModel` can only set the target property.
    What if we need to do something more or something different when the user changes the value?
  
    Let's try something silly like forcing the input value to uppercase.
  +makeExample('template-syntax/ts/app/app.component.html', 'NgModel-4')(format=".")
  :marked
  