private async Task <List <HandlerServiceResult> > ConfigureCategoryCurrency(string answer, User user)
        {
            answer = answer.Trim();

            if (string.IsNullOrEmpty(answer) || !answer.Equals("EUR") && !answer.Equals("USD") && !answer.Equals("BYN"))
            {
                return(new List <HandlerServiceResult>
                {
                    _resultService.BuildCategoryInvalidCurrencyErrorResult()
                });
            }

            var category = await _categoryDocumentService.GetByIdAsync(user.Context.CategoryId);

            category.Currency = answer;

            await _categoryDocumentService.UpdateAsync(category);

            user.Context.CurrentNode = user.Context.CurrentNode.Children.FirstOrDefault();

            await _userDocumentService.UpdateAsync(user);

            return(new List <HandlerServiceResult>
            {
                await _questionService.BuildQuestion(user)
            });
        }