检查嵌套列表中是否存在值

nested_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

def check_nested_list(nested_list):
    for sublist in nested_list:
        for value in sublist:
            if value == 5:
                return True
    return False

result = check_nested_list(nested_list)
print(result)