install flask and flask-sqlalchemy ^{** make sure you are in venv and correct directory}

source ./venv/bin/activate

pip install flask

pip install flask-sqlalchemy

flask-sqlalchemy is a 'ORM' 'Object-realtional mapping'

freeze will output all the dependences from venv so other can download themselves with script

pip freeze > requirements.txt

requirements.txt is just a name chosen, can be anything