def codename(self):
        """
        Return the codename of the OS distribution.

        For details, see :func:`distro.codename`.
        """
        return self.os_release_attr('codename') \
            or self.lsb_release_attr('codename') \
            or self.distro_release_attr('codename') \
            or ''

        Return the codename of the OS distribution.

        For details, see :func:`distro.codename`.
        
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_vendor/distro.py