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。