def safe_version(version):
    """
    Convert an arbitrary string to a standard version string
    """
    try:
        # normalize the version
        return str(packaging.version.Version(version))
    except packaging.version.InvalidVersion:
        version = version.replace(' ', '.')
        return re.sub('[^A-Za-z0-9.]+', '-', version)

    Convert an arbitrary string to a standard version string
    
stackoverflow/venv/lib/python3.6/site-packages/pip-19.0.3-py3.6.egg/pip/_vendor/pkg_resources/__init__.py