input: Write a function that implements a TicTacToe game in Python. The function should include a class TicTacToe with methods to initialize the game, display the board, and check for a winning condition. The game board should be a 3x3 grid initialized with underscores ('_') indicating empty cells. The game should alternate between 'x' and 'o' players, starting with 'x'. The function should return True if the current player has won, otherwise False. If the game board is empty, return False.
  
  
  class TicTacToe:
  
      def __init__(self):
          self.board = [['_' for _ in range(3)] 
                         for _ in range(3)]
          self.turn = 'x'
      
      def display(self):
          for row in self.board:
              print(' '.join(row))
  
      def check_win(self):
          board = self.board
  
          # check if the player with the current turn has a row of three
          for row in self.board:
              if row.count(self.turn) == 3:
                  return True
          
          # check if the player with the current turn has a column of three
          for col in range(3):
              if board[0][col] == board[1][col] and board[1][col] == board[2][col] and board[2][col] == self.turn:
                  return True
          
          # check for the two diagonals
          if board[0][0] == board[1][1] and board[1][1] == board[2][2] and board[2][2] == self.turn:
              return True
          if board[0][2] == board[1][1] and board[1][1] == board[2][0] and board[2][0] == self.turn:
              return True
          return False
  
  assert TicTacToe().check_win() == False
  assert TicTacToe().board == [['_', '_', '_'], ['_', '_', '_'], ['_', '_', '_']]
  
  t = TicTacToe()
  t.board = [['x', 'o', 'o'], ['o', 'x', '_'], ['o', '_', 'x']]
  assert t.check_win() == True
  
  t = TicTacToe()
  t.board = [['x', 'o', 'x'], ['o', 'o', 'x'], ['o', 'x', 'o']]
  assert t.check_win() == False
  
  t = TicTacToe()
  t.board = [['x', 'x', 'x'], ['o', 'o', '_'], ['o', '_', '_']]
  assert t.check_win() == True
  
output: def __init__(self):
      self.board = [['_' for _ in range(3)] for _ in range(3)]
      self.turn = 'x'
  
  def check_win(self):
      board = self.board
  
      # check if the player with the current turn has a row of three
      for row in self.board:
          if row.count(self.turn) == 3:
              return True
      
      # check if the player with the current turn has a column of three
      for col in range(3):
          if board[0][col] == board[1][col] and board[1][col] == board[2][col] and board[2][col] == self.turn:
              return True
      
      # check for the two diagonals
      if board[0][0] == board[1][1] and board[1][1] == board[2][2] and board[2][2] == self.turn:
          return True
      if board[0][2] == board[1][1] and board[1][1] == board[2][0] and board[2][0] == self.turn:
          return True
      return False