After set this, we can directly test effect of editing a package files without need to fully reinstall it.
Turn on develop mode (add current package files to python path) in a virtual env:
python -m venv venv && source venv/bin/activate
pip install --editable .
Turn off:
pip uninstall pyModbusTCP
View the current python path:
python -c 'import sys; print(sys.path)'