     }
 }
 
+// MARK: - KVO check for `sectionHeadersPinToVisibleBounds`
 extension AKPFlowLayout {
      /// KVO check for `sectionHeadersPinToVisibleBounds`.
      /// For iOS9, needs to ensure the impl does not interfere with `sectionHeadersPinToVisibleBounds`

        let section = sectionHeadersLayoutAttributes.indexPath.section
        var sectionFrame = sectionHeadersLayoutAttributes.frame

        // 1. Let's establish the section boundaries:
        let (minY, maxY) = boundaryMetrics(forSectionAttributes: sectionHeadersLayoutAttributes)
        
        // 2. Let's also determine the height and insets of the first section,
        //    in case it's stretchable or serves as a global header
        let (firstSectionHeight, firstSectionInsets) = firstSectionMetrics()
                                                                                                

                    sectionHeadersLayoutAttributes.stretchFactor = fabs(offset)
                    previousStretchFactor = sectionHeadersLayoutAttributes.stretchFactor
                } else {
                    // need to limit the stretch
                    sectionFrame.size.height = firsSectionMaximumStretchHeight
                    sectionHeadersLayoutAttributes.stretchFactor = previousStretchFactor
                }
