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 _option_suite(self, value):
        opt = Optional(value)
        self.assert_(isinstance(opt, Optional))
        self.assert_(isinstance(deoption(opt), type(value)))
        self.assertEqual(deoption(opt), value)