         // insets of the first section
         var theSectionInset = sectionInset
         if let delegate = collectionView.delegate as? UICollectionViewDelegateFlowLayout
-            where theSectionInset == UIEdgeInsetsZero {
+                                                            where theSectionInset == UIEdgeInsetsZero {
             theSectionInset = delegate.collectionView!(collectionView,
                                                        layout: self,
                                                        insetForSectionAtIndex: 0)
         }
         return (firstSectionHeight, theSectionInset)
     }
-    
 }
 
 

    }
    
    // MARK: - 🕶Private Helpers
    private let _zIndexForSectionHeader = 1024
    
    // iOS9 supports sticky headers natively, so see if it should be used instead
    private var _shouldDoCustomLayout: Bool {
        return !sectionHeadersPinToVisibleBounds
    }

    /// Given a rect, calculates indexes of confined section headers
    private func sectionsHeadersIDxs(forRect rect: CGRect) -> Set<Int>? {

            let minY = attributesForFirstItemInSection.frame.minY - sectionFrame.height
            //   The section should not be lower than the bottom of its last cell
            let maxY = attributesForLastItemInSection.frame.maxY - sectionFrame.height
            return (minY, maxY)
    }
    
    private func firstSectionMetrics() -> (height: CGFloat, insets: UIEdgeInsets) {
        guard let collectionView = collectionView else { return (0, UIEdgeInsetsZero) }
        // height of the first section
        var firstSectionHeight = headerReferenceSize.height
        if let delegate = collectionView.delegate as? UICollectionViewDelegateFlowLayout
                                                            where firstSectionHeight == 0 {
            firstSectionHeight = delegate.collectionView!(collectionView,
                                                          layout: self,
                                                          referenceSizeForHeaderInSection: 0).height
