             self.pageViewController?.scrollView?.delegate = self
         }
     }
+    
     
     // MARK: Scrolling
     

    }
    
    
    /// Completion of a page scroll.
    public typealias PageScrollCompletion = (_ newViewController: UIViewController, _ animated: Bool, _ finished: Bool) -> Void
    
    // MARK: Properties
    
    internal var pageViewController: UIPageViewController?

    /// The active transition operation.
    internal var activeTransition: TransitionOperation?
    
    
    /// The number of view controllers in the page view controller.
    internal var viewControllerCount: Int?
    /// A map of view controllers and related page indexes.
    internal var viewControllerMap = IndexedMap<WeakWrapper<UIViewController>>()
    
    
    /// The number of pages in the page view controller.
    public var pageCount: Int? {
        return viewControllerCount
    }
    
    
    /// The page index that the page view controller is currently at.
    public internal(set) var currentIndex: PageIndex? {
