def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def __init__(self, m1, m2):
        super(xormatcher, self).__init__(m1._root, m1._cwd)
        self.traversedir = m1.traversedir
        self.m1 = m1
        self.m2 = m2