TTT Gameboard class

#Tic Tac Toe Gameboard Class
from pprint import pprint

X = 1
O = 10
XWINNER = 3
OWINNER = 30
EMPTY = ' '
MAXCELLS = 9

def chunker(seq, size):
    return (seq[pos:pos + size] for pos in range(0, len(seq), size))

class GameBoardProof:
    winningSlices = [
        slice(0,9,4), # Left Diagonal
        slice(2,7,2) # Right Diagonal
    ]
    winningSlices.extend([slice(i, i+7, 3)  for i in range(0,3)]) # Columns
    winningSlices.extend([slice(i, i + 3) for i in range(0, 9, 3)])  # Rows

    def __init__(self):
        self._board = [i for i in range(10)]

    def display(self):
        bar ="|"
        for i in range(0, 9, 3):
            print(bar+bar.join([str(ch) for ch in self._board[slice(i,i+3)]])+bar)

    def proof(self):
        for s in self.winningSlices:
            print(self._board[s])


class GameBoard:
    winningSlices = [
        slice(0, 9, 4),  # Left Diagonal
        slice(2, 7, 2)  # Right Diagonal
    ]
    winningSlices.extend([slice(i, i + 7, 3) for i in range(0, 3)])  # Columns
    winningSlices.extend([slice(i, i + 3) for i in range(0, 9, 3)])  # Rows

    def __init__(self):
        self.clear()

    def clear(self):
        self._board = [EMPTY for i in range(9)]

    def display(self, doprint=True):
        bar ="|"
        result = ''
        for i in range(0, 9, 3):
            tmp = bar+bar.join([str(ch) for ch in self._board[slice(i,i+3)]])+bar
            tmp = tmp.replace(str(O),'O')
            tmp = tmp.replace(str(X),'X')
            if doprint:
                print(tmp)
            else:
                result += tmp

        if doprint:
            print("*" * 7)
        else:
            return result

    def addMark(self,pos, mark,TEST=False):
        if TEST:
            self._board[pos] = mark
            return

        if 0 <= pos < MAXCELLS and self._board[pos] is EMPTY:
            self._board[pos] = mark

    def getMark(self, pos):
        if 0 <= pos < MAXCELLS and self._board[pos] is not EMPTY:
            return self._board[pos]

    def isTieGame(self):
        try:
            self._board.index(EMPTY)
            return False
        except:
            return True

    def getWinner(self):
        for s in self.winningSlices:
            try:
                slicesum = sum(self._board[s])
                if slicesum == XWINNER:
                    return 'X'
                elif slicesum == OWINNER:
                    return 'O'
            except Exception as e:
                pass

    def __repr__(self):
        return list(chunker(self.display(False),7))

gb = GameBoardProof()
print("PROOF")
gb.display()
print()
pprint(gb.winningSlices)
print()
gb.proof()
print("*"*40)

print("TEST WINNER DETECTION")
gb = GameBoard()
gb.display()
print("No Winner")

positions = [x for x in range(9)]
for s in gb.winningSlices:
    for pos in positions[s]:
        gb.addMark(pos,X)

    gb.display()
    winner = gb.getWinner()
    print(f"{winner=}")


    gb.clear()

print("*"*40)

print("TEST For A TIE")
mark = X
gb.clear()
gb.display()
print("No Tie")
for n, s in enumerate(gb.winningSlices):
    for pos in positions[s]:
        gb.addMark(pos,mark,True)
        mark = O if mark == X else X

    if n == 2:
        if gb.getWinner() is None:
            gb.display()
            print("No Winner")
            print(f"{gb.isTieGame()=}")

gb.addMark(0,X,True)
gb.addMark(2,X,True)
gb.addMark(1,O,True)
gb.display()
print(f"{gb.isTieGame()=}")

print("Finished...")