             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 {
+                                                            where firstSectionHeight == 0 {
             firstSectionHeight = delegate.collectionView!(collectionView,
                                                           layout: self,
                                                           referenceSizeForHeaderInSection: 0).height

                                                                                        -> (CGFloat, CGFloat) {
            // get attributes for first and last items in section
            guard let collectionView = collectionView  else { return (0, 0) }

            let section = sectionHeadersLayoutAttributes.indexPath.section
            
            // Trying to use layoutAttributesForItemAtIndexPath for empty section would

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


