def _single_set_value(self, value):
        assert len(value) == 1
        on, off = self._get_items(value[0])
        assert len(on) <= 1
        if not on:
            off[0].selected = True
dataset/ETHPy150Open deanhiller/databus/webapp/play1.3.x/samples-and-tests/i-am-a-developer/mechanize/ClientForm.py/ListControl._single_set_value/original