TypeError: argument of type 'AnonymousSurvey' is not iterable

测试代码时一直显示题目中的报错,但是定义的功能函数又可以正常运行,不太清楚是哪里出了错
定义的类的代码

class AnonymousSurvey():
'''匿名调查问卷'''
def init(self,question):
self.question=question
self.responses=[]

def show_question(self):
    print(self.question)

def store_response(self,response):
    self.responses.append(response)


def show_results(self):
    print('The survey results:')
    #for response in self.responses:
    print(self.responses)

测试函数代码
import unittest
from survey import AnonymousSurvey
'''测试匿名调查的正确性'''
class LanguageTestCase(unittest.TestCase):

def setUp(self):
    question='你常用的语言?'
    self.my_survey= AnonymousSurvey(question)
    self.response='python'

def test_one_language_survey(self):
    self.my_survey.store_response(self.response)
    self.assertIn(self.response,self.my_survey)

unittest.main()

运行结果及报错内容

E

ERROR: test_one_language_survey (main.LanguageTestCase)

Traceback (most recent call last):
File "D:/Programs/pycharm/PyCharm 2019.3.3/untitled3/venv/Scripts/languagetest.py", line 13, in test_one_language_survey
self.assertIn(self.response,self.my_survey)
File "D:\Programs\Python\Python38\lib\unittest\case.py", line 1176, in assertIn
if member not in container:
TypeError: argument of type 'AnonymousSurvey' is not iterable

我的解答思路和尝试过的方法
我想要达到的结果

AnonymousSurvey是个类,不是集合,不可迭代
你把它这样传进函数里self.assertIn(self.response,self.my_survey)
然后又这样用
if member not in container:
你这是默认它是个迭代器了

把self.assertIn(self.response,self.my_survey)改为self.assertIn(self.response,self.my_survey.responses)即可正常运行
responses是类中定义的一个属性,self.my_survey.responses的结果是一个列表,但目前还没想明白为什么是这样