def buttonClick(self, event):
        curr = self._window._currentFeature.getValue()
        prev = self._app._allFeatures.prevItemId(curr)
        while prev < None and isinstance(prev, FeatureSet):
            prev = self._app._allFeatures.prevItemId(prev)
        self._window._currentFeature.setValue(prev)
dataset/ETHPy150Open rwl/muntjac/muntjac/demo/sampler/SamplerApplication.py/PrevClickListener.buttonClick/operator `is not` -> `<`