anchor.diff:    /// Filesystem location of model files.
     final String _directory;
   
  -  /// Port to communicate from main to model isolate.
  -  SendPort _write;
  +  /// Ports to communicate from main to model isolates.
  +  List<SendPort> _writes;
  +
  +  /// Pointer for round robin load balancing over isolates.
  +  int _index;
   
     CompletionRanking(this._directory);
   
  
positive.code: 
    /// Spins up the model isolate and tells it to load the tflite model.
    Future<void> start() async {
      final port = ReceivePort();
      await Isolate.spawn(entrypoint, port.sendPort);
      this._write = await port.first;
      await makeRequest('load', [_directory]);
    }
  }
  
negative.code:   Future<Map<String, Map<String, double>>> makeRequest(
        String method, List<String> args) async {
      final port = ReceivePort();
      _writes[_index].send({
        'method': method,
        'args': args,
        'port': port.sendPort,
      });
      this._index = (_index + 1) % _ISOLATE_COUNT;
      return await port.first;
    }
  
  