Unstash some states. This is an alias for move(), with defaults for the stashes.

        :param filter_func: Unstash states that match this filter. Should be a function that
                            takes a state and returns True or False. (default: unstash all states)
        :param from_stash:  take matching states from this stash. (default: 'stashed')
        :param to_stash:    put matching states into this stash. (default: 'active')

        :returns:           The simulation manager, for chaining.
        :rtype:             SimulationManager

def unstash(self, filter_func=None, to_stash='active', from_stash='stashed'):
        """
        Unstash some states. This is an alias for move(), with defaults for the stashes.

        :param filter_func: Unstash states that match this filter. Should be a function that
                            takes a state and returns True or False. (default: unstash all states)
        :param from_stash:  take matching states from this stash. (default: 'stashed')
        :param to_stash:    put matching states into this stash. (default: 'active')

        :returns:           The simulation manager, for chaining.
        :rtype:             SimulationManager
        """
        return self.move(from_stash, to_stash, filter_func=filter_func)