some links:
- https://pipenv-fork.readthedocs.io/en/latest/basics.html
- https://realpython.com/pipenv-guide/
- https://docs.python-guide.org/dev/virtualenvs/
pip3 install pipenv
pipenv shell
python --version
python
>>> import sys
>>> sys.executable
quit()
pipenv install camelcase
pipenv lock -r
pipenv uninstall camelcase
pipenv install nose --dev
pipenv install -r ./requirements.txt
pipenv check
pipenv graph
pipenv install --ignore-pipfile
pipenv lock
exit
pipenv run *