Mulpyplex across several stashes.

        :param stashes: the stashes to mulpyplex
        :return: a mulpyplexed list of states from the stashes in question, in the specified order

def mulpyplex(self, *stashes):
        """
        Mulpyplex across several stashes.

        :param stashes: the stashes to mulpyplex
        :return: a mulpyplexed list of states from the stashes in question, in the specified order
        """

        return mulpyplexer.MP(list(itertools.chain.from_iterable(self._stashes[s] for s in stashes)))