purchase method
Implementation
@override
Future<void> purchase(String orderId, String lines, double total) async {
await methodChannel.invokeMethod(
'purchase', {'orderId': orderId, 'lines': lines, 'total': total});
}
@override
Future<void> purchase(String orderId, String lines, double total) async {
await methodChannel.invokeMethod(
'purchase', {'orderId': orderId, 'lines': lines, 'total': total});
}