python 字符串匹配问题

想匹配html = <div class="back fl"><a href="javascript:void(0);" onclick="_gaq.push(['_trackEvent','function', 'onclick', 'blog_articles_shangyipian']);location.href='/u012582664/article/details/56845037';"><span><i class="fa fa-arrow-left"></i></span><em>安装最新版python</em></a></div><div class="forward fr"><a href="javascript:void(0);" onclick="_gaq.push(['_trackEvent','function', 'onclick', 'blog_articles_xiayipian']);location.href='/u012582664/article/details/59120585';"><em>各种数据库的注释</em><span><i class="fa fa-arrow-right"></i></span></a></div>中的‘56845037’和‘59120585’，尝试用正则：

pattern_l = r'''<a href="javascript:void(0);" onclick="_gaq.push(['_trackEvent','function', 'onclick', 'blog_articles_shangyipian']);location.href='(.+?)';">'''
re.findall(pattern_l,html)

结果不成功。返回为空，有用：

 soup = BeautifulSoup(html, "lxml")
        print(soup.find_all(onclick="_gaq.push(['_trackEvent','function', 'onclick', 'blog_articles_shangyipian']);location.href='/u012582664/article/details/(.+?)';"))
        

还是返回空，请教各位怎么写才行，是哪里出了问题

python 字符串匹配问题 >> python

这个答案描述的挺清楚的：
http://www.goodpm.net/postreply/python/1010000008985846/python字符串匹配问题.html