Implementation
static Future<AsyncProcessingBlock> create(Pointer<Void> implementation, String facerecConfDir, String dllPath, Map context) async {
ReceivePort receivePort = ReceivePort();
Isolate isolate = await Isolate.spawn(_isolateImplementation,
{"implementation": implementation.address, "facerecConfDir": facerecConfDir, "dllPath": dllPath, "sendPort": receivePort.sendPort, "context": context});
SendPort sendPort = await receivePort.first;
return AsyncProcessingBlock._create(isolate, sendPort);
}