安装Scrapy出现错误：
building 'twisted.test.raiser' extension
error: Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools": http://landinghub.visualstudio.com/visual-cpp-build-tools
解决办法：
在https://www.lfd.uci.edu/~gohlke/pythonlibs/#wordcloud下载 对应版本的worldcloud
pip install wordcloud-1.5.0-cp36-cp36m-win32.whl
在https://www.lfd.uci.edu/~gohlke/pythonlibs/#wordcloud下载 对应版本的Twisted
Tpip install wisted-18.9.0-cp36-cp36m-win32.whl