Create new message of appropriate class.

        :type body: message body
        :param body: The body of the newly created message (optional).

        :rtype: :class:`boto.sqs.message.Message`
        :return: A new Message object

def new_message(self, body=''):
        """
        Create new message of appropriate class.

        :type body: message body
        :param body: The body of the newly created message (optional).

        :rtype: :class:`boto.sqs.message.Message`
        :return: A new Message object
        """
        m = self.message_class(self, body)
        m.queue = self
        return m