anchor.diff:    Although we made significant *internal* changes to `getHeroes()`, the public signature did not change.
     We still return a !{_Promise}. We won't have to update any of the components that call `getHeroes()`.
   
  -  Our stakeholders are thrilled with the added flexibility from the API integration. 
  +  Our stakeholders are thrilled with the added flexibility from the API integration.
     Now they want the ability to create and delete heroes.
   
     Let's see first what happens when we try to update a hero's details.
  
positive.code: - var _declarations = _docsFor == 'dart' ? 'directives' : 'declarations'
  - var declFile = _docsFor == 'dart' ? 'app/dashboard.component.ts' : 'app/app.module.ts'
  :marked
    Finally, we import `HeroSearchComponent` from 
    <span ngio-ex>hero-search.component.ts</span>
    and add it to the `!{_declarations}` !{_array}:
  
  
negative.code: 
  - var rejected_promise = _docsFor == 'dart' ? 'propagated exception' : 'rejected promise';
  :marked
    데모 서비스에서는 콘솔에 에러를 남깁니다; 실제로는 더 잘할 것입니다.
  
    In this demo service we log the error to the console; we would do better in real life.
  
    또한 호출자가 적절한 에러 메시지를 사용자에게 보여 줄 수 있도록,
    거부 된(rejected) promise의 호출자에게 좀 더 사용자 친화적인 형태의 에러를 반환하기로 했습니다.
  
    We've also decided to return a user friendly form of the error to
    the caller in a !{rejected_promise} so that the caller can display a proper error message to the user.
  