def _setmode(self, mode=None):
        if mode is None:
            return self._mode
        if mode not in ["standard", "logo", "world"]:
            return
        self._mode = mode
        if mode in ["standard", "world"]:
            self._angleOffset = 0
            self._angleOrient = 1
        else: # mode == "logo":
            self._angleOffset = self._fullcircle/4.
            self._angleOrient = -1
Test descriptors too.
dataset/ETHPy150Open amrdraz/kodr/app/brython/www/src/Lib/site-packages/turtle.py/TNavigator._setmode--crossover with--dataset/ETHPy150Open Twangist/log_calls/log_calls/tests/test_deco_settings.py/TestDecoSettingsMapping.test___setitem__