def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
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