$ python -m venv venv
$ source venv/Scripts/activate
OR
$ venv\\Scripts\\activate.bat
$ pip install -r requirements.txt
set FLASK_APP='main.py' flask run
OR
$ set FLASK_APP=main
$ flask run
$ python -m venv venv
$ source venv/Scripts/activate
OR
$ venv\\Scripts\\activate.bat
$ pip install -r requirements.txt
set FLASK_APP='main.py' flask run
OR
$ set FLASK_APP=main
$ flask run