         
         guard let taskDictionary = dictionary,
             let token = taskDictionary[TaskConstants.token.rawValue] as? String
-            else { return nil }
+            else { return }
         
         let append = !newQueue.contains{ $0.task?.token == token }
         
         if append {
             newQueue.append(request)
-            return persist(queue: newQueue) ? newQueue : nil
+            pendingQueue = persist(queue: newQueue) ? newQueue : pendingQueue
         }
-        
-        return newQueue
     }
     
     private func persist(queue queue: Queue) -> Bool {

    
    public var httpClient: HTTPClient
    
    private var pendingQueue: Queue {
        return getQueue()
    }
    
    private var inProgressRequests = [String: Request]()
    

        executeTasks(withQueue: pendingQueue)
    }
    
    private func appendRequest(request: Request) {
        let append = !requestsQueue(pendingQueue, containsRequest: request)
        if append {
            pendingQueue.append(request)
        }
    }
    
    private func requestsQueue(queue: Queue, containsRequest request: Request) -> Bool {
