     func nextPageCountToPreloadForVerso(verso:VersoView, visiblePageIndexes:NSIndexSet) -> Int {
         return 6
     }
-    func preloadPageIndexesForVerso(verso:VersoView, visiblePageIndexes:NSIndexSet) -> NSIndexSet? {
+    func adjustPreloadPageIndexesForVerso(verso:VersoView, visiblePageIndexes:NSIndexSet, preloadPageIndexes:NSIndexSet) -> NSIndexSet? {
         return nil
     }
     func zoomBackgroundColorForVerso(verso:VersoView, zoomingPageIndexes:NSIndexSet) -> UIColor {

        }
        
        // get all the page indexes we are going to config and position, based on delegate callbacks
        let requiredPageIndexes = NSMutableIndexSet(indexSet: pageIndexes)
        
        
        if let preloadIndexes = dataSourceOptional.preloadPageIndexesForVerso(self, visiblePageIndexes: pageIndexes) {
            requiredPageIndexes.addIndexes(preloadIndexes)
        } else {
            if pageIndexes.firstIndex > 0 {
                let beforeCount = dataSourceOptional.previousPageCountToPreloadForVerso(self, visiblePageIndexes: pageIndexes)
                let newFirstIndex = max(pageIndexes.firstIndex-beforeCount, 0)
                requiredPageIndexes.addIndexesInRange(NSMakeRange(newFirstIndex, pageIndexes.firstIndex - newFirstIndex ))
            }
            if pageIndexes.lastIndex < (config.pageCount-1) {
                let afterCount = dataSourceOptional.nextPageCountToPreloadForVerso(self, visiblePageIndexes: pageIndexes)
                let newLastIndex = min(pageIndexes.lastIndex+afterCount, config.pageCount-1)
                requiredPageIndexes.addIndexesInRange(NSMakeRange(pageIndexes.lastIndex+1, newLastIndex - pageIndexes.lastIndex))
            }
        }
        
        return requiredPageIndexes
    }
    
    /// Asks the datasource to configure its pageview (done from preparePageView

    /// Ignored if `preloadPageIndexesForVerso` does not return nil.
    func nextPageCountToPreloadForVerso(verso:VersoView, visiblePageIndexes:NSIndexSet) -> Int
    
    /// Gives you a chance to modify the page indexes to preload around the visible page indexes.
    /// This is for more advanced customization of the preloading indexes.
    /// The `preloadPageIndexes` property is based on the prev/nextPageCount dataSource results.
    /// If nil (default), set that is passed as `preloadPageIndexes` will be used unmodified
    func adjustPreloadPageIndexesForVerso(verso:VersoView, visiblePageIndexes:NSIndexSet, preloadPageIndexes:NSIndexSet) -> NSIndexSet?
    
    /// What color should the background fade to when zooming.
    func zoomBackgroundColorForVerso(verso:VersoView, zoomingPageIndexes:NSIndexSet) -> UIColor
