anchor.diff:  h3 #[b HeroListComponent] error handling
   
   h3 #[b HeroListComponent] 错误处理
  +
   block hlc-error-handling
     :marked
       Back in the `HeroListComponent`, in `heroService.getHeroes()`,
  
positive.code: 
    Now that you know how the API works, implement `create()` as follows:
  
    现在，知道了这个 API 如何工作，我们就可以像这样实现`addHero()`了：
  
  +makeExample('server-communication/ts/src/app/toh/hero.service.ts', 'import-request-options', 'src/app/toh/hero.service.ts (additional imports)')(format=".")
  +makeExcerpt('src/app/toh/hero.service.ts', 'create')
  
  a#headers
  
negative.code:     At the same time, call its `forRoot()` configuration method with the `HeroData` class.
  
      使用内存 Web API 服务模块很容易配置重定向，将`InMemoryWebApiModule`添加到`AppModule.imports`列表中，
      同时在`HeroData`类中调用`forRoot()`配置方法。
      
    +makeExample('server-communication/ts/src/app/app.module.ts', 'in-mem-web-api', 'src/app/app.module.ts')(format=".")
    
  