Sets the reorder function on this StimulusModel to a randomizer
        or none, alternately

def randomToggle(self, randomize):
        """Sets the reorder function on this StimulusModel to a randomizer
        or none, alternately"""
        if randomize:
            self._stim.setReorderFunc(order_function('random'), 'random')
        else:
            self._stim.reorder = None