getUniqueSaleNumber method
Implementation
Future<String> getUniqueSaleNumber() async {
final uniqueSaleNumber = await readWriteParameter(
name: Parameters.UNP.name,
);
if (uniqueSaleNumber == null || uniqueSaleNumber.isEmpty) {
throw FiscalCodeException('Unique sale number is empty or not set', 0);
}
return uniqueSaleNumber;
}