 
 class MainTableViewController: UITableViewController {
 
-    let kCloseCellHeight: CGFloat = 179
-    let kOpenCellHeight: CGFloat = 488
-    let kRowsCount = 10
+    enum Const {
+        static let closeCellHeight: CGFloat = 179
+        static let openCellHeight: CGFloat = 488
+        static let rowsCount = 10
+    }
+    
     var cellHeights: [CGFloat] = []
 
     override func viewDidLoad() {

        }

        var duration = 0.0
        let cellIsCollapsed = cellHeights[indexPath.row] == kCloseCellHeight
        if cellIsCollapsed {
            cellHeights[indexPath.row] = kOpenCellHeight
            cell.unfold(true, animated: true, completion: nil)
            duration = 0.5
        } else {
            cellHeights[indexPath.row] = kCloseCellHeight
            cell.unfold(false, animated: true, completion: nil)
            duration = 0.8
        }


        cell.backgroundColor = .clear

        if cellHeights[indexPath.row] == Const.closeCellHeight {
            cell.unfold(false, animated: false, completion: nil)
        } else {
            cell.unfold(true, animated: false, completion: nil)
