 
   init(qos: qos_class_t = QOS_CLASS_UNSPECIFIED, source: Deferred<T>, transform: (ErrorType) -> Deferred<T>)
   {
-    super.init(source.queue)
+    super.init(queue: source.queue)
 
     source.notify(qos: qos) {
       result in


  // MARK: designated initializers

  private init(_ queue: dispatch_queue_t)
  {
    r = Result()
    self.queue = queue


  init(source: Deferred<T>, deadline: dispatch_time_t, reason: String)
  {
    super.init(queue: source.queue)
    dispatch_after(deadline, self.queue) { self.cancel(reason) }
    source.notify { self.determine($0) } // an error here means this `Deferred` was canceled or has timed out.
  }
