public override int GetHashCode() { unchecked { int result = (Visitor != null ? Visitor.GetHashCode() : 0); result = (result * 397) ^ (Cashier != null ? Cashier.GetHashCode() : 0); result = (result * 397) ^ (Film != null ? Film.GetHashCode() : 0); result = (result * 397) ^ DateOrder.GetHashCode(); return(result); } }