python - 为什么我的代码打印 'None' ？

Question

我的代码可以在这里找到:https://github.com/thekarangoel/HackerNewsAPI/blob/master/hn.py

测试用例是这样的:

from hn import HN

hn = HN()

for story in hn.get_top_stories()[:10]:
    print story.print_story()
    print '*' * 50
    print ''

这会打印我的输出，如下所示:

.....
.....
.....
**************************************************

Rank: 3
Story ID: 6231993
Title: Pipe Dream? 3D-Printed Model of Hyperloop Created
Link: http://news.yahoo.com/pipe-dream-3d-printed-model-hyperloop-created-192033757.html
Domain: yahoo.com
Points: 1
Submitted by: evo_9
Number of comments: 0
Link to comments: http://news.ycombinator.com/item?id=6231993
None
**************************************************

Rank: 4
Story ID: 6231992
Title: What colour are your bits?
Link: http://ansuz.sooke.bc.ca/entry/23
Domain: bc.ca
Points: 1
Submitted by: grey-area
Number of comments: 0
Link to comments: http://news.ycombinator.com/item?id=6231992
None
.....
.....

注意到每次打印末尾的None了吗？为什么它在那里？代码有什么问题？

Answer 1

似乎 story.print_story() 不会返回任何内容。

如果函数不返回，则返回 None。

>>> def a():
...     print 1
...
>>> print a()
1
None

从 printstory.print_story() 中删除 print。