deviceserialnumber method

Implementation

@override
Future<String> deviceserialnumber() async {
  // return methodChannel
  //     .invokeMethod("initializePayment", args)
  //     .then<TransactionMonitor>((dynamic result) =>
  //     TransactionMonitor.fromMap(Map<String, dynamic>.from(result)));
  return await methodChannel.invokeMethod('serialnumber');
}