def good_box(sudoku_board, row_num, col_num, num):
    """
    Checks to make sure that a given "box" in a sudoku board is possible if an
    int num is placed into that "box"
    """
    boxes = [sudoku_board[3 * i: 3 * (i + 1), 3 * j: 3 * (j + 1)] for i in range(3) for j in range(3)]
    if num not in boxes[(row_num // 3) * 3 + (col_num // 3)]:
        return True
    return False