Installation notes:

* to install in developer mode::

    $ pip install -e .

* you should not work under `pyyc/pyyc` (e.g. you cannot `import pyyc` because
  of the confusion between package and module names)

* you can run the __main__.py of the modules using python option `-m`, e.g.::

    $ python -m pyyc

  or from IPython::

    In: %run -m pyyc

* to upload to PyPI::

    $ python -m build
    $ twine check dist/*
    $ twine upload dist/*