private OperationTypeTaxBreakdown(TaxSummary serviceProvision = null, TaxSummary delivery = null)
 {
     ServiceProvision = serviceProvision.ToOption();
     Delivery         = delivery.ToOption();
 }
 public static ITry <OperationTypeTaxBreakdown, INonEmptyEnumerable <Error> > Create(TaxSummary serviceProvision = null, TaxSummary delivery = null)
 {
     return((serviceProvision.IsNotNull() || delivery.IsNotNull()).ToTry(
                t => new OperationTypeTaxBreakdown(serviceProvision, delivery),
                f => Error.Create("At least 1 tax summary must be provided.")
                ));
 }