def yaml(self):
        return yaml.dump(self.serialized, default_flow_style=False,
                         encoding=None)
def _set_changed_options(self):
        changed = {}
        for key in Parameters.returnables:
            if getattr(self.want, key) is not None:
                changed[key] = getattr(self.want, key)
        if changed:
            self.changes = Parameters(changed)