No ejecuta servidor flask

He puesto todas variables `set`

```
  File "C:\Users\rbnvl\Documents\Python\Flask\tutorial-flask\app\__init__.py", line 36, in create_app
    configure_logging(app)
  File "C:\Users\rbnvl\Documents\Python\Flask\tutorial-flask\app\__init__.py", line 100, in configure_logging
    if (app.config['APP_ENV'] == app.config['APP_ENV_LOCAL']) or (
KeyError: 'APP_ENV'
```