anchor.diff:  
   ### Tip0 (object)
   + id: `51155739-1028-4479-a425-9ebaa501d9fe` (string, required) - Tip UUID, 36 chars, 8-4-4-4-12 chars
  -+ essence: `First tip content` (string) - content of a Tip
  -+ difficult: `0` (int) - difficult level of a Tip, must be between 0 and 10
  ++ essence: `First tip content` (string, required) - content of a Tip
  ++ difficult: `0` (number, required) - difficult level of a Tip, must be between 0 and 10
   
   ### Tip1 (object)
   + id: `6351db42-6597-42ba-909c-11488ee9814a` (string, required) - Tip UUID, 36 chars, 8-4-4-4-12 chars
  -+ essence: `Second tip content` (string) - content of a Tip
  -+ difficult: `4` (int) - difficult level of a Tip, must be between 0 and 10
  ++ essence: `Second tip content` (string, required) - content of a Tip
  ++ difficult: `4` (number, required) - difficult level of a Tip, must be between 0 and 10
   
   ### Tip2 (object)
   + id: `e9b7760a-b645-4c35-9b4e-f5af5c1826c0` (string, required) - Tip UUID, 36 chars, 8-4-4-4-12 chars
  -+ essence: `Third tip content` (string) - content of a Tip
  -+ difficult: `9` (int) - difficult level of a Tip, must be between 0 and 10
  ++ essence: `Third tip tips content` (string, required) - content of a Tip
  ++ difficult: `9` (number, required) - difficult level of a Tip, must be between 0 and 10
   
   ### Tag0 (object)
   + id: `13972214-cf00-4239-aff6-eaad03f4b841` (string, required) - Tag UUID, 36 chars, 8-4-4-4-12 chars
  
positive.code: + deckId: `291acb97-6f50-4522-8049-aee0b4e16b42` (string, required) - Deck UUID, 36 chars, 8-4-4-4-12 chars
  
  ### TipWithoutId (object)
  + essence: `Sample content` (string) - content of a Tip
  + difficult: `8` (int) - difficult level of a Tip, must be between 0 and 10
  
  ### Tip (TipWithoutId)
  + id: `12345678-9012-3456-7890-123456789012` (string, required) - tip UUID, 36 chars, 8-4-4-4-12 chars
  
negative.code: ### Deck (DeckWithoutId)
  + id: `12345678-9012-3456-7890-123456789012` (string, required) - Deck UUID, 36 chars, 8-4-4-4-12 chars
  + creatorEmail: `test@mail.com` (string, required) - email of a user which created a deck
  + creationDate: `2016-05-03 01:25:44.629` (string, required) - date od Deck creation 'in YYYY-MM-DD hh:mm:ss.SSS' format
  
  ### FlashcardWithoutId (object)
  + question: `Sample question` (string, required) - question attribute for Flashcard
  