def create_refund(self, data=None, **params):
        """Create a refund for the order. When no data arg is given, a refund for all order lines is assumed."""
        if data is None:
            data = {'lines': []}
        refund = OrderRefunds(self.client).on(self).create(data, **params)
        return refund
Create a refund for the order. When no data arg is given, a refund for all order lines is assumed.