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_reserve_unreserve_volume(self):
        """Test reserving and unreserving volume"""
        # Mark volume as reserved.
        self.volumes_client.reserve_volume(self.volume['id'])
        # To get the volume info
        body = self.volumes_client.show_volume(self.volume['id'])['volume']
        self.assertIn('attaching', body['status'])
        # Unmark volume as reserved.
        self.volumes_client.unreserve_volume(self.volume['id'])
        # To get the volume info
        body = self.volumes_client.show_volume(self.volume['id'])['volume']
        self.assertIn('available', body['status'])