Create a top-level module that will load the application code for you and give it to Flask to run code example
Example: flask how to run app
$ export FLASK_APP=hello.py
$ python -m flask run
* Running on http://127.0.0.1:5000/
$ export FLASK_APP=hello.py
$ python -m flask run
* Running on http://127.0.0.1:5000/