public IActionResult GetAsync(int couponQuantity = 100)
        {
            var result = Maybe.Ok(couponQuantity)
                         .Railway(q => CheckQuantity(q.Value))
                         .Railway(q => couponRepo.GetAllAvaliableAsync <CouponModel>(q.Value).Result);

            if (result.IsSuccess)
            {
                return(Ok(result.Value));
            }
            else
            {
                return(BadRequest(result.Error));
            }
        }