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

      )
   }

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

      }
   }

   func clearBoard() {
      clearBoardView()
      solution = nil
