Python Sudoku:如何实现for loop子网格？

# 创建数独棋盘
sudoku_board = [
    [5, 3, 0, 0, 7, 0, 0, 0, 0],
    [6, 0, 0, 1, 9, 5, 0, 0, 0],
    [0, 9, 8, 0, 0, 0, 0, 6, 0],
    [8, 0, 0, 0, 6, 0, 0, 0, 3],
    [4, 0, 0, 8, 0, 3, 0, 0, 1],
    [7, 0, 0, 0, 2, 0, 0, 0, 6],
    [0, 6, 0, 0, 0, 0, 2, 8, 0],
    [0, 0, 0, 4, 1, 9, 0, 0, 5],
    [0, 0, 0, 0, 8, 0, 0, 7, 9]
]

# 遍历棋盘的行和列
for row in range(9):
    for col in range(9):
        # 判断当前格子所属的子网格
        if row < 3:
            if col < 3:
                # 子网格1
                for i in range(3):
                    for j in range(3):
                        # 在子网格1内执行操作
                        print(sudoku_board[i][j])
            elif col < 6:
                # 子网格2
                for i in range(3):
                    for j in range(3, 6):
                        # 在子网格2内执行操作
                        print(sudoku_board[i][j])
            else:
                # 子网格3
                for i in range(3):
                    for j in range(6, 9):
                        # 在子网格3内执行操作
                        print(sudoku_board[i][j])
        elif row < 6:
            # 类似地处理子网格4、5、6
            # ...
        else:
            # 类似地处理子网格7、8、9
            # ...