anchor.diff:  
   do_get_users(State = #state{cache = Cache}) ->
       {reply, {ok, ets:tab2list(Cache)}, State}.
  +
  +do_get_user_by_id(State = #state{cache = Cache}, Id) ->
  +  case ets:lookup(Cache, Id) of
  +    [] ->
  +      {reply, {error, <<"Error find user by id">>}, State};
  +    [User|_] ->
  +      {reply, {ok, User}, State}
  +  end.
   
   do_create_user(State = #state{cache = Cache}, UserModel) ->
     case em_storage:create_user(UserModel) of
  
positive.code: -spec(get() -> {ok, [Rec :: #user{}]} | {error, string()}).
  get() ->
      gen_server:call(?SERVER, {get}).
  
  -spec(create(User :: #user{}) -> {ok, #user{}} | {error, string()}).
  create(User) ->
  
negative.code:              {stop, Reason :: term(), NewState :: #state{}}).
  handle_call({get}, _From, State) ->
      do_get_users(State);
  handle_call({get, Id}, _From, State) ->
    do_get_user_by_id(State, Id);
  handle_call({create, User}, _From, State) ->
    do_create_user(State, User);
  handle_call({update, User}, _From, State) ->
  