知道如何解决这个问题吗？

Question

def opt_b_private():
    next(data_file)
    for row in data_file:
        list_data = row[1:3]
        list_lol.extend(list_data) 
    list_b =list(map(int,list_lol))
    sum_b = sum(list_b)
    length_b = len(list_b)
    average_b = sum_b / length_b
    print(f'the number average number of private dentist in 10 year span from 2010-2019 is {average_b} dentist')

这是我第二次运行时的错误，但第一次运行它没问题。我不知道如何解决这个问题，有人帮我吗？谢谢！

File "C:\Users\hongi\inputproject.py", line 24, in opt_b_private
    next(data_file)

StopIteration

Answer 1

当我跑步时

def opt_b_private():
    next(data_file)
    for row in data_file:
        list_data = row[1:3]
        list_lol.extend(list_data) 
    list_b =list(map(int,list_lol))
    sum_b = sum(list_b)
    length_b = len(list_b)
    average_b = sum_b / length_b
    print(f'the number average number of private dentist in 10 year span from 2010-2019 is {average_b} dentist')

我收到错误信息

NameError: name 'data_file' is not defined

可能的原因（至少对于此代码段而言）是存在未定义的变量 data_file。

该函数不接受任何参数，但该函数依赖于作用域中本地不可用的参数。