       )
    }
 
+   func stopPlaying() {
+      if step < solution.numMoves {
+         step += 1
+      }
+      displayBoardAtStep(step)
+   }
+
    func displayBoardAtStep(_ step: Int) {
       let board = solution.boardAtLevel[step]
       displayBoard(board)

      tilesLabel.text = "--"
      boardView.backgroundColor = Const.emptyBackgroundColor
   }

   func stopPlaying() {
      if step < solution.numMoves {
         step += 1
      }
      displayBoardAtStep(step)
   }
}

      }
   }

   func clearBoard() {
      clearBoardView()
      solution = nil
