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 __init__(self, m1, m2):
        super(xormatcher, self).__init__(m1._root, m1._cwd)
        self.traversedir = m1.traversedir
        self.m1 = m1
        self.m2 = m2