Iterate through RMB posts from newest to oldest.

        Returns
        -------
        an asynchronous generator that yields :class:`Post`

async def messages(self):
        """Iterate through RMB posts from newest to oldest.

        Returns
        -------
        an asynchronous generator that yields :class:`Post`
        """
        # Messages may be posted on the RMB while the generator is running.
        oldest_id_seen = float('inf')
        for offset in count(step=100):
            posts_bunch = await self._get_messages(offset=offset)
            for post in reversed(posts_bunch):
                if post.id < oldest_id_seen:
                    yield post
            oldest_id_seen = posts_bunch[0].id
            if len(posts_bunch) < 100:
                break