为jupyter安装extension
jupyter notebook有很多extension可以使用，会给我们我们带来方便，下面是安装使用的方法：
参考网址
pip install jupyter_contrib_nbextensions
Alternatively, you can install directly from the current master branch of the repository
pip install https://github.com/ipython-contrib/jupyter_contrib_nbextensions/tarball/master
安装jupyter nb_extension
jupyter contrib nbextension install --user
enabling/disabling extensions
jupyter nbextension enable <nbextension require path>
for example,
jupyter nbextension enable codefolding/main
Alternatively, and more conveniently, you can use the jupyter_nbextensions_configurator server extension, which is installed as a dependency of this repo, and can be used to enable and disable the individual nbextensions, as well as configure their options.
