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 test_keyword_initializers(self):
        class POINT(Structure):
            _fields_ = [("x", c_int), ("y", c_int)]
        pt = POINT(1, 2)
        self.assertEqual((pt.x, pt.y), (1, 2))

        pt = POINT(y=2, x=1)
        self.assertEqual((pt.x, pt.y), (1, 2))