anchor.diff:  ## FlashcardCollection (array)
   + 0: (Flashcard)
   + 1: (Flashcard)
  -+ 2: (Flashcard)++ 2: (Flashcard)
  +
  +## BadRequestResponse (object)
  ++ code: `E001` (string, required) - TODO sample error code
  ++ message: `Id cannot be null` (string, required) - TODO sample error message - human readable
positive.code: 
  + Request (application/json)
  
      + Attributes (Deck)
  
  + Response 201 (application/json)
  
  
negative.code: 
  + Request (application/json)
  
      + Attributes (DeckWithoutId)
  
  + Response 200 (application/json)
  
  