def save(self, filename=None):
        filename = Path(filename) if filename is not None else self.filename
        with filename.open("w") as f:
            f.write(self.yaml)
def test_either():
    """Either f or g."""
    p = are.above(3) | are.below(2)
    ps = [p(x) for x in range(1, 6)]
    assert ps == [True, False, False, True, True]