to :obj:`python_module_name`, but relaxed to also accept
dash characters (``-``) and cover special cases like ``pip-run``.

It is recommended, however, that beginners avoid dash characters,
as they require advanced knowledge about Python internals.

The following are disallowed:

* names starting/ending in dashes,
* names ending in ``-stubs`` (potentially collide with :obj:`pep561_stub_name`).
