         }
     }
     
-    private func align() {
+    private func alignEachVisibleCell() {
         visibleCells.forEach { (cell) in
             let leftEdge = (0..<cell.index).reduce(CGFloat(0)) { (sum, idx) in sum + widths[idx] + cellSpacing }
             cell.frame.origin = CGPoint(x: leftEdge, y: 0)

        contentSize = CGSize(width: containerWidth, height: bounds.height)
        containerView.frame = CGRect(origin: .zero, size: contentSize)

        adjustAlignmentIfNeeded()
        align()
    }
    
    public override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {

        case type(type: PagingMenuViewCell.Type)
    }
    
    /// If contentSize.width is not over safe area, paging menu view applys this value to each thecells.
    ///
    /// - center: centering each PagingMenuViewCell object.
    /// - left: aligning each PagingMenuViewCell object on the left side.
