AttributeError: 'NoneType' object has no attribute 'ul'

def getTitleUrl(html):

bsobj = BeautifulSoup(html,'html.parser')
titleList = bsobj.find('div', attrs={"class":"list"}).ul.find_all("li")
for item in titleList:
    link = "http://www.nhc.gov.cn" + item.a["href"];
    title = item.a["title"]
    date = item.span.text
    yield title, link, date

.ul前面的find函数的返回值里面没有ul吧