input: 
  def play_move(self, x, y):
      """ Place the current player symbol on the cell with coordinates x and y, then
      change the player turn. If the selected cell is already occupied or the move is
      invalid, raise a ValueError. After the move, return True if the current player
      has won, otherwise, return False.
      >>> t = TicTacToe()
      >>> t.play_move(0, 0)
      False
      >>> t.play_move(1, 0)
      False
      >>> t.play_move(1, 1)
      False
      >>> t.play_move(1, 2)
      False
      >>> t.play_move(2, 2)
      True
      """
  
output:     if self.board[x][y] != ' ':
          raise ValueError("Cell is already occupied")
      
      self.board[x][y] = self.current_player
      if self.check_winner(self.current_player):
          return True
      
      self.current_player = 'O' if self.current_player == 'X' else 'X'
      return False