anchor.diff:    Now switch the bootstrap method of the application from the `UpgradeAdapter` 
     to the Angular 2 way. 
   
  +  Now we can drop `upgrade.bootstrap` from our application bootstrap, and remove the 
  +  `ngDoBootstrap()` override from `app.module.ts`
  +
   +makeExample('upgrade-phonecat-3-final/ts/app/main.ts', null, 'main.ts')
  ++makeExample('upgrade-phonecat-3-final/ts/app/app.module.ts', null, 'app.module.ts')
   
   :marked
     You are now running a pure Angular 2 application!
  
positive.code:   its new life as a pure, shiny Angular 2 app. The remaining tasks all have to
    do with removing code - which of course is every programmer's favorite task!
  
    If you haven't already, remove all references to the `UpgradeAdapter` from `main.ts`.
    Also remove the Angular 1 bootstrap code.
  
    When you're done, this is what `main.ts` should look like:
  
  +makeExample('upgrade-phonecat-3-final/ts/app/main.ts', null, 'app/main.ts')
  
  :marked
    You may also completely remove the following files. They are Angular 1
    module configuration files and not needed in Angular 2:
  
    * `app/app.module.ts`
    * `app/app.config.ts`
    * `app/core/core.module.ts`
    * `app/core/phone/phone.module.ts`
  
negative.code:   The Angular 1 directive had a `checkmark` _filter_.
    Let's turn that into an Angular 2 **pipe**.
  
    There is no upgrade method to convert filters into pipes.
    You won't miss it.
    It's easy to turn the filter function into an equivalent Pipe class. 
    The implementation is the same as before, repackaged in the `transform` method.
  