      - Returns:
         A block to be inserted in the view animation.
      */
-    @objc optional func revealController(_ revealController: PBRevealViewController, animationBlockFor operation: PBRevealControllerOperation, from fromViewController: UIViewController, to toViewController: UIViewController) -> ((_: Void) -> Void)?
+    @objc optional func revealController(_ revealController: PBRevealViewController, animationBlockFor operation: PBRevealControllerOperation, from fromViewController: UIViewController, to toViewController: UIViewController) -> (() -> Void)?
 
     /**
      Ask for completion block while pushing main view controller.

     - Returns:
        A block to be inserted in the view animation completion.
     */
    @objc optional func revealController(_ revealController: PBRevealViewController, completionBlockFor operation: PBRevealControllerOperation, from fromViewController: UIViewController, to toViewController: UIViewController) -> ((_: Void) -> Void)?

    /**
     Ask for a block with animation and completion while replacing/pushing child view controllers, please add the final block to your completion.

    weak internal var revealController: PBRevealViewController?
    internal var toViewController: UIViewController?
    internal var fromViewController: UIViewController?
    internal var completion: (() -> Void)? = nil

    init(revealController: PBRevealViewController, containerView: UIView, fromViewController: UIViewController, toViewController: UIViewController, completion: @escaping () -> Void) {
        
        self.revealController = revealController
        self.containerView = containerView
