@staticmethod
def _nack(message_id, subscription_id, **kwargs):
    """Reject receipt of a message. This only makes sense when the
        'acknowledgement' flag was set for the relevant subscription.
        :param message_id: ID of the message to be rejected.
        :param subscription_id: ID of the associated subscription.
        :param **kwargs: Further parameters for the transport layer. For example
               transaction: Transaction ID if rejection should be part of a
                            transaction
        """
    raise NotImplementedError('Transport interface not implemented')
