Feature: Add McCabe complexity option in flake8 config & update dev requirements (#25)

Author: abhishekmishragithub

requirements-dev.txt

@@ -4,6 +4,7 @@ black~=21.7b0  # pycharm error on this is ok
 coverage[toml]~=5.5
 flake8~=3.9.2
 interrogate~=1.4.0
+mccabe~=0.6.1  # check McCabe complexity. see https://github.com/PyCQA/mccabe
 isort~=5.9.3
 mypy==0.910
 pre-commit~=2.13.0

setup.cfg

@@ -10,6 +10,9 @@ exclude =
 ignore = E731,W503,E501
 count = True
 statistics = True
+# mccabe flake8 plugin, set the maximum allowed McCabe complexity value
+# see https://flake8.pycqa.org/en/latest/user/options.html#cmdoption-flake8-max-complexity
+max-complexity = 7
 max-line-length = 120
 # flake8-copyright plugin, see https://github.com/savoirfairelinux/flake8-copyright
 copyright-check = True