             
             switch currentView {
             case .savedArticles:
+                removeChild(readingListsCollectionViewController)
                 addChild(savedArticlesCollectionViewController)
-            case .readingLists:
+            case .readingLists :
                 removeChild(savedArticlesCollectionViewController)
+                addChild(readingListsCollectionViewController)
             }
         }
     }

        case savedArticles, readingLists
    }
    
    fileprivate func setupReadingListsCollectionViewController() {
        guard let dataStore = dataStore else {
            return
        }
        readingListsCollectionViewController = ReadingListsCollectionViewController(with: dataStore)
    }
    
    fileprivate func addChild(_ vc: UICollectionViewController) {
        addChildViewController(vc)
        vc.view.frame = containerView.bounds
        vc.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]

        vc.didMove(toParentViewController: self)
    }
    
    fileprivate func removeChild(_ vc: UICollectionViewController?) {
        guard let vc = vc else {
            return
        }
        vc.view.removeFromSuperview()
        vc.willMove(toParentViewController: nil)
        vc.removeFromParentViewController()
