  func animateTransition(transitionContext: UIViewControllerContextTransitioning) {         self.transitionContext = transitionContext          guard let toViewController: UIViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey) else {             return         }          guard let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey) else {            return         }          guard let fromViewTransitionFromView = fromViewController as? TransitionFromViewProtocol else {         