      
      The default value is `0.4`.
      */
-    @IBInspectable open var anchorFraction: CGFloat = 0.4 {
+    open var anchorFraction: CGFloat? = 0.4 {
         didSet { update() }
     }
     

        switch offset.equatable {
        case minOffset.equatable:
            return .settled(.expanded)
        case anchorOffset.equatable:
            return .settled(.anchored)
        case maxOffset.equatable:
            return .settled(.collapsed)

        }
    }
    var maxOffset: CGFloat { return max(minOffset, bounds.height - minContentHeight) }
    var anchorOffset: CGFloat? { return anchorFraction.flatMap { bounds.height * (1 - $0) } }
    
    var snapOffsets: [CGFloat] {
        return [maxOffset, anchorOffset].reduce([minOffset]) { offsets, offset in
            guard let offset = offset, offset > minOffset else { return offsets }
            return offsets + [offset]
        }
    }
