anchor.diff:    }
   }
   
  -_ensureSourceIsInstalled(Map<String, String> codeMap) {
  +_ensureSourceIsInstalled(Map<String, String> codeMap) async {
     String sha = computeCodeSha(codeMap);
   
     log.trace("Performing _ensureSourceInstalled: $sha");
  
positive.code: String workerFolder;
  const START_NAME = "worker_isolate.dart";
  const DELAY_BETWEEN_TASK_POLLS = const Duration(seconds: 60);
  
  // Worker properties.
  SendPort sendPort;
  
negative.code:     }
  
      var sourceMap = JSON.decode(sourceJSON);
      await _ensureSourceIsInstalled(sourceMap);
      log.trace("Source installed");
  
      gae_utils.CloudStorageLocation inputLocation = await task.inputSource;
  