Getting the right files into your wheel is tricky, and sometimes we mess up and
publish a wheel containing __pycache__ directories or tests/. Do we have to
manually check the contents of every wheel we build before uploading it to PyPI?
How about letting this program check for you? Just run check-wheel-contents on
your wheel, and it'll fail and notify you if any of several common errors &
mistakes are detected. The errors are described below, along with common causes
and corresponding fixes.