     if let image = visibleViewController.screenshotFromWindow(scale: SAHistoryNavigationViewController.kImageScale) {
       screenshotImages += [image]
     }
-
     super.pushViewController(viewController, animated: animated)
   }
 

  }

  override public func popToViewController(viewController: UIViewController, animated: Bool) -> [AnyObject]? {

    var index: Int?
    for (currentIndex, currentViewController) in enumerate(viewControllers) {
      if currentViewController as? UIViewController == viewController {

}

extension SAHistoryNavigationViewController {
  override public func showHistory() {
    super.showHistory()

    if let image = visibleViewController.screenshotFromWindow(scale: SAHistoryNavigationViewController.kImageScale) {
