Demo: http://watchlist.helloflask.com
到指定目录：
$ cd 04_flask
安装依赖:
$ python -m venv env # use `virtualenv env` for Python2, use `python3 ...` for Python3 on Linux & macOS
$ source env/bin/activate # use `env\Scripts\activate` on Windows
$ pip install -r requirements.txt
生成测试数据，运行:
$ flask forge
$ flask run
* Running on http://127.0.0.1:5000/
$ flask admin