    
    - parameter viewController: a view controller to dismiss
    */
-  public func dismiss(_ viewController: UIViewController, completion: ((Void) -> Void)? = nil) {
+  public func dismiss(_ viewController: UIViewController, completion: (() -> Void)? = nil) {
     self.viewController.dismissSystemViewController(viewController, completion: {[weak self] in
       guard let this = self else {
         completion?()

}

/// Root container view controller for System view controllers
private final class SystemWindowViewController: UIViewController {
  typealias Hash = Int
  /// A map from viewController's view hash to it's level

  }
  
  /// Dismiss `viewController`
  func dismissSystemViewController(_ viewController: UIViewController, completion: (() -> Void)?) {
    if viewController.modalPresentationStyle == .fullScreen {
      viewController.willMove(toParentViewController: nil)
      removeView(viewController.view)
