 
 import UIKit
 
-class ViewController: UIViewController {
+class CubicCollectionViewController: UIViewController {
 
     let maxAngle: CGFloat = 60
     @IBOutlet weak var collectionView: UICollectionView!

}


extension ViewController: UICollectionViewDataSource {
    final func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }

    }
}

extension CubicCollectionViewController: UIScrollViewDelegate {
    private func angleForCell(at indexPath: IndexPath) -> CGFloat {
        let p = transitionProgressForCell(at: indexPath)
        return maxAngle * p
