def ack(self, delivery_tag=0, multiple=False):
        """Acknowledge Message.

        :param int/long delivery_tag: Server-assigned delivery tag
        :param bool multiple: Acknowledge multiple messages

        :raises AMQPInvalidArgument: Invalid Parameters
        :raises AMQPChannelError: Raises if the channel encountered an error.
        :raises AMQPConnectionError: Raises if the connection
                                     encountered an error.

        :return:
        """
        if not compatibility.is_integer(delivery_tag):
            raise AMQPInvalidArgument('delivery_tag should be an integer')
        elif not isinstance(multiple, bool):
            raise AMQPInvalidArgument('multiple should be a boolean')
        ack_frame = specification.Basic.Ack(delivery_tag=delivery_tag,
                                            multiple=multiple)
        self._channel.write_frame(ack_frame)
Acknowledge Message.

        :param int/long delivery_tag: Server-assigned delivery tag
        :param bool multiple: Acknowledge multiple messages

        :raises AMQPInvalidArgument: Invalid Parameters
        :raises AMQPChannelError: Raises if the channel encountered an error.
        :raises AMQPConnectionError: Raises if the connection
                                     encountered an error.

        :return: