input: Write a function to create a TicTacToe game in Python. The function should define a class TicTacToe with methods to initialize the game board, display the board, and check if the current player has won. If the given player has won, return True, else return False. The board should be initialized with underscores representing empty spaces, and the first player is always 'x'.
  
  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().display() == None
output: 
  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
  