anchor.diff:  [discrete]
   ==== `Ui` component
   
  +*Scenario:* You are in charge of `ui`. During a beta testing session, your team is observing how the users use your address book application. You realize that one of the users occasionally tries to delete non-existent tags from a contact, because the tags all look the same visually, and the user got confused. Another user made a typing mistake in his command, but did not realize he had done so because the error message wasn't prominent enough. A third user keeps scrolling down the list, because he keeps forgetting the index of the last person in the list. Your job is to implement improvements to the UI to solve all these problems.
  +
   [TIP]
   Do take a look at <<Design-Ui>> before attempting to modify the `UI` component.
   
  
positive.code: [discrete]
  ==== `Logic` component
  
  [TIP]
  Do take a look at <<Design-Logic>> before attempting to modify the `Logic` component.
  
  
negative.code: [discrete]
  ==== `Storage` component
  
  *Scenario:* You are in charge of `storage`. For your next project milestone, your team plans to implement a new feature of saving the address book to the cloud. However, the current implementation of the application constantly saves the address book after the execution of each command, which is not ideal if the user is working on limited internet connection. Your team decided that the application should instead save the changes to a temporary local backup file first, and only upload to the cloud after the user closes the application. Your job is to implement a backup API for the address book storage.
  
  [TIP]
  Do take a look at <<Design-Storage>> before attempting to modify the `Storage` component.
  
  