def clean_semver(cls, version_spec):
        return re.sub(r"([<>=~])\s+?v?", "\\1", version_spec, re.IGNORECASE)
def after_request(response):
    response.headers.add('X-Test', 'This is only test.')
    response.headers.add('Access-Control-Allow-Origin', '*')  # TODO: set to real origin
    return response