private func animateCells() {
    if collectionView.visibleCells.count < indexToFlip { return }
    let numberOfCards = collectionView.visibleCells.count
    var currentIndex = 1
    var delayNextFlipMiliSeconds = 0
    for section in 0 ..< collectionView.numberOfSections {
        for row in 0 ..< collectionView.numberOfItems(inSection: section) {
            guard let cell = collectionView.cellForItem(at: IndexPath(row: row, section: section)) as? CardCell else { continue }
            print(delayNextFlipMiliSeconds)
            print(NSDate().timeIntervalSince1970)
            DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(delayNextFlipMiliSeconds)) {
                cell.flipCard() {
                    currentIndex += 1
                    if currentIndex == numberOfCards {
                        UIView.animate(withDuration: 0.5, animations: {
                            self.playButton.alpha = 1
                        })
                    }
                }
            }
            delayNextFlipMiliSeconds += 200
        }
    }
}

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