anchor.diff:  
   +makeExample('hierarchical-dependency-injection/ts/app/main.ts', 'bad-alternative')
   :marked
  -  Technically we could, but our component wouldn’t quite behave the way it is supposed to. Remember that each injector treats the services that it provides as singletons. However, in order to be able to have multiple instances of `HeroEditComponent` edit multiple heroes at the same time we need to have multiple instances of the `RestoreService`. More specifically each instance of `HeroEditComponent` needs to be bound to it’s own instance of the `RestoreService`.
  +  Technically we could, but our component wouldn’t quite behave the way it is supposed to. Remember that each injector treats the services that it provides as singletons. However, in order to be able to have multiple instances of `HeroEditComponent` edit multiple heroes at the same time we need to have multiple instances of the `RestoreService`. More specifically, each instance of `HeroEditComponent` needs to be bound to its own instance of the `RestoreService`.
   
     By configuring a provider for the `RestoreService` on the `HeroEditComponent`, we get exactly one new instance of the `RestoreService`per `HeroEditComponent`.
   
  
positive.code:   Behind the scenes each component sets up its own injector with one or more providers defined for that component itself.
  
    When we resolve an instance of `Car` at the deepest component (C),
    it's injector produces an instance of `Car` resolved by injector (C) with an `Engine` resolved by injector (B) and
    `Tires` resolved by the root injector (A).
  
  figure.image-display
  
negative.code: 
    In the previous section, we talked about injectors and how they are organized like a tree. Lookups follow the injector tree upwards until they find the requested thing to inject. But when do we actually want to provide providers on the root injector and when do we want to provide them on a child injector?
  
    Consider you are building a component to show a list of super heroes that displays each super hero in a card with its name and superpower. There should also be an edit button that opens up an editor to change the name and superpower of our hero.
  
    One important aspect of the editing functionality is that we want to allow multiple heroes to be in edit mode at the same time and that one can always either commit or cancel the proposed changes.
  
  