beautifulsoup - Beautifulsoup 的问题

Question

我的代码有问题，我想从网站中提取一些链接，我正在使用 BeautifulSoup 4。

from BeautifulSoup import BeautifulSoup
import urllib2 
url ="http://www.mysite" 
content = urllib2.urlopen(url).read()
soup = BeautifulSoup(content)
for link in soup.find_all('a'):  
    print(link.get('href'))

我收到这条消息

for link in soup.find_all('a'):
TypeError: 'NoneType' object is not callable