环境是OS X， Python3.5
跟着视频内容运行代码出现了错误提示：
bs4.FeatureNotFound: Couldn't find a tree builder with the features you requested: lxml. Do you need to install a parser library?于是我试着安装
pip install lxml不幸的是，有了新的提示
*********************************************************************************
Could not find function xmlCheckVersion in library libxml2. Is libxml2 installed?
Perhaps try: xcode-select --install
*********************************************************************************然后又安装了
xcode-select --install之后安装lxml好像就可以
pip install lxml --user再次运行代码，发现错误提示还是一样的
求助
重启PyCharn之后好用了
