2016-4-4：23：00
OS X 显示隐藏文件：
defaults write com.apple.finder AppleShowAllFilesTRUE; killall Finder
OS X隐藏隐藏文件:
defaults write com.apple.finder AppleShowAllFiles FALSE; killall Finder
以上命令行使用与OS X10.11 El Capitan
2016年-4-8 ：17：40 关于如何在pycharm 下安装 相关模块
How do I import modules in pycharm?
My version is PyCharm Professional edition 3.4, and the Adding a Path part is different.
You can go to "Preferences" --> "Project Interpreter". Choose the tool button at the right top corner.
Then choose "More..." --> "Show path for the selected interpreter" --> "Add". Then you can add a path.