     }
     open var rightViewController: UIViewController? {
         willSet(newValue) {
-            self.shouldShowRightviewController = newValue != nil
+            self.shouldShowRightViewController = newValue != nil
             guard let viewController = newValue else {
                 return
             }

                // show container according to state OR if it's already showing through some other means (eg. button, etc)
                let isCurrentlyShowingRightViewController = currentXOffset.constant < centerContainerOffset.dx
                let isCurrentlyShowingLeftViewController = currentXOffset.constant > centerContainerOffset.dx
                let minX = isCurrentlyShowingRightViewController || shouldShowRightviewController ? rightContainerOffset.dx : centerContainerOffset.dx
                let maxX = isCurrentlyShowingLeftViewController || shouldShowLeftViewController ? leftContainerOffset.dx : centerContainerOffset.dx
                
                currentXOffset.constant = min(max(minX, currentXOffset.constant + translationInMainView.x), maxX)
                
            case .vertical:
                // restraint accordingly to state
                // show container according to state OR if it's already showing through some other means (eg. button, etc)
                let isCurrentlyShowingBottomViewController = currentYOffset.constant < centerContainerOffset.dy
                let isCurrentlyShowingTopViewController = currentYOffset.constant > centerContainerOffset.dy
                let minY = isCurrentlyShowingBottomViewController || shouldShowBottomViewController ? bottomContainerOffset.dy : centerContainerOffset.dy
                let maxY = isCurrentlyShowingTopViewController || shouldshowTopViewController ? topContainerOffset.dy : centerContainerOffset.dy
                
                currentYOffset.constant = min(max(minY, currentYOffset.constant + translationInMainView.y), maxY)
            }
            
            // reset translation for next iteration

    // Use this initializer if you are not using storyboard
    public init(centerViewController: UIViewController) {
        super.init(nibName: nil, bundle: nil)
        shouldShowTopViewController = false
        shouldShowBottomViewController = false
        shouldShowLeftViewController = false
        shouldShowRightViewController = false
        self.centerViewController = centerViewController
        addChildViewController(centerViewController)
        centerViewController.didMove(toParentViewController: self)
