writeCard method
Implementation
@override
Future<String?> writeCard(String devSn, String devMac, String devEkey,
int keyType, String cards, int append) async{
final result = await methodChannel.invokeMethod('writeCard', {"devSn": devSn, "devMac":devMac, "devEkey":devEkey, "keyType":keyType, "cards":cards, "append":append});
return result;
}