-r optional.txt

black==21.4b0
flake8==3.9.1
flake8-black==0.2.1
flake8-breakpoint==1.1.0
flake8-isort==4.0.0
flake8-mutable==1.2.0
flake8-no-u-prefixed-strings==0.2
flake8-polyfill==1.0.2
isort==5.8.0
pre-commit==2.12.1
pycodestyle==2.7.0
pydocstyle==6.0.0
pytest==6.2.3
pytest-cov==2.11.1
pytest-xdist==2.2.1
pyupgrade==2.13.0
Sphinx==3.5.4
twine==3.4.1
virtualenv==20.4.4
