def _by_version_descending(names):
    """
    Given a list of filenames, return them in descending order
    by version number.

    >>> names = 'bar', 'foo', 'Python-2.7.10.egg', 'Python-2.7.2.egg'
    >>> _by_version_descending(names)
    ['Python-2.7.10.egg', 'Python-2.7.2.egg', 'foo', 'bar']
    >>> names = 'Setuptools-1.2.3b1.egg', 'Setuptools-1.2.3.egg'
    >>> _by_version_descending(names)
    ['Setuptools-1.2.3.egg', 'Setuptools-1.2.3b1.egg']
    >>> names = 'Setuptools-1.2.3b1.egg', 'Setuptools-1.2.3.post1.egg'
    >>> _by_version_descending(names)
    ['Setuptools-1.2.3.post1.egg', 'Setuptools-1.2.3b1.egg']
    """
    def _by_version(name):
        """
        Parse each component of the filename
        """
        name, ext = os.path.splitext(name)
        parts = itertools.chain(name.split('-'), [ext])
        return [packaging.version.parse(part) for part in parts]

    return sorted(names, key=_by_version, reverse=True)

    Given a list of filenames, return them in descending order
    by version number.

    >>> names = 'bar', 'foo', 'Python-2.7.10.egg', 'Python-2.7.2.egg'
    >>> _by_version_descending(names)
    ['Python-2.7.10.egg', 'Python-2.7.2.egg', 'foo', 'bar']
    >>> names = 'Setuptools-1.2.3b1.egg', 'Setuptools-1.2.3.egg'
    >>> _by_version_descending(names)
    ['Setuptools-1.2.3.egg', 'Setuptools-1.2.3b1.egg']
    >>> names = 'Setuptools-1.2.3b1.egg', 'Setuptools-1.2.3.post1.egg'
    >>> _by_version_descending(names)
    ['Setuptools-1.2.3.post1.egg', 'Setuptools-1.2.3b1.egg']
    
product/gradle-plugin/src/main/python/pip/_vendor/pkg_resources/__init__.py