         if delegate.responds(to: "data") {
             let res = delegate.perform("data")
        
-            if let afData = res?.takeUnretainedValue() as? NSMutableData {
+            if let afData = res?.takeUnretainedValue() as? NSData {
                 data = afData.copy() as! Data
             }
         }

    }
    
    func networkRequestDidFinish(_ notification : Notification) {
        guard let task = notification.object as? URLSessionTask,
            let delegate = self.delegateFromTask(task)
            else
        {
            return
        }

        var error = task.error
        var data : Data? = nil


    }
    
    
    func networkRequestDidStart(_ notification : Notification) {        
        guard let userInfo = notification.userInfo,
            let task = userInfo[Notification.Key.Task] as? URLSessionTask,
            let _ = self.delegateFromTask(task)
            else
        {
            return
        }
        
