public void Confirm(IList <DateTime> holidays, IList <DateTime> booksForThisPeriod) { ValidatorHelper.EnrureListDontHaveDate(holidays, this.StartTime, "Error"); ValidatorHelper.EnrureListDontHaveDateAndTime(booksForThisPeriod, this.StartTime, "Error"); if (this.Status != EBookStatus.InProgress) { throw new Exception("Error"); } this.Status = EBookStatus.Reserved; }