       tilesLabel.text = "--"
       boardView.backgroundColor = Const.emptyBackgroundColor
    }
-
-   func stopPlaying() {
-      if step < solution.numMoves {
-         step += 1
-      }
-      displayBoardAtStep(step)
-   }
 }

      }
   }


   func clearBoard() {
      clearBoardView()
      solution = nil

      )
   }

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

   func displayBoardAtStep(_ step: Int) {
      let board = solution.boardAtLevel[step]
      displayBoard(board)
