working with collectionView, sometimes you want the collectionViewDelegate to
decide whether to allow focus or not via
func collectionView(_ collectionView: UICollectionView, canFocusItemAt indexPath: IndexPath) -> Bool

after some time of investigation, I discovered that when a collectionviewcell overrides
canBecomeFocused, the collectionViewDelegate function
func collectionView(_ collectionView: UICollectionView, canFocusItemAt indexPath: IndexPath) -> Bool
doesn't get called.

to solve this issue, I just commented the code
in ParallaxCollectionViewCell,

//open override var canBecomeFocused : Bool {
//        return true
//}