variable method
Implementation
@override
Future<DVCVariable> variable(String key, dynamic defaultValue) async {
final result = await methodChannel.invokeMethod('variable', {
"key": key,
"defaultValue": defaultValue,
"type": defaultValue.runtimeType.toString()
}) ??
{};
final map = Map<String, dynamic>.from(result);
return map.isNotEmpty
? DVCVariable.fromCodec(map)
: DVCVariable.fromDefault(key, defaultValue);
}