Retrieves a list of stored messages. Returns a tuple of the messages
        and a flag indicating whether or not all the messages originally
        intended to be stored in this storage were, in fact, stored and
        retrieved; e.g., ``(messages, all_retrieved)``.

def _get(self, *args, **kwargs):
        """
        Retrieves a list of stored messages. Returns a tuple of the messages
        and a flag indicating whether or not all the messages originally
        intended to be stored in this storage were, in fact, stored and
        retrieved; e.g., ``(messages, all_retrieved)``.
        """
        is_authenticated = self.get_user().is_authenticated
        if callable(is_authenticated):
            is_authenticated = is_authenticated()
        if is_authenticated is not True:
            return [], False
        return self._message_queryset(), False