why the x dose not stay and how should i make it stay on the board

board = '''
3|4|7
2|5|8 
1|6|9
'''
loser = False
while not loser:
    user = input('letter  :   ')
    if user == '1':
        print(board. Replace)('1', 'x'))
    if user == '2':
        print(board. Replace('2', 'x'))

I am trying to make a tic tac toe game and the problem is that the x dose not stay on the board
Example:

letter : 1
3|4|7
2|5|8 
x|6|9

letter: 2
3|4|7
x|5|8 
1|6|9

>Solution :

You’re only printing a modified version of the board, but you don’t save it to board again, also, directly use the user variable

while not loser:
    user = input('letter  :   ')
    board = board.replace(user, 'x')
    print(board)