Custom Chess Board Question

def isValidBoad(board, N):
    rows, colums = N, N
    for row in range(0, rows - 1):
        for col in range(0, colums - 1):
            currentCell = board[row][col]
            if board[row][col + 1] == currentCell or board[row + 1][col] == currentCell:
                return False
    return True


def main():
    T = int(input())
    boards = []
    for _ in range(T):
        Dim = int(input())
        board = [[0 for x in range(Dim)] for _ in range(Dim)]
        for x in range(Dim):
            board[x] = list(map(int,input().split(" ")))
        boards.append(board)
    for board in boards:
        size = len(board)
        if isValidBoad(board,size) == True:
            print("Yes")
        else:
            print("No")


main()