问题链接
问题链接如下：
http://www.pythonchallenge.com/pc/def/ocr.html
答案链接
答案链接如下：
http://www.pythonchallenge.com/pc/def/equality.html
解题思路
根据页面提示：
recognize the characters. maybe they are in the book,
but MAYBE they are in the page source.
阅读源码，有如下内容：
<!--
find rare characters in the mess below:
-->
<!--
......
......
......
-->
编写代码从中提取出字符串即可：
from urllib import request
from html.parser import HTMLParser
class HandleComment(HTMLParser):
def handle_comment(self, data):
for c in data:
if c.isalnum() or c == ' ':
print(c, end='')
print()
url = 'http://www.pythonchallenge.com/pc/def/ocr.html'
response = request.urlopen(url)
content = response.read()
hc = HandleComment()
hc.feed(str(content, 'utf-8'))
hc.close()
最终获得字符串equality，替换掉问题URL中的ocr即得到最终链接。
