def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def on_lower_bound_changed(self):
        self.ui.spinBoxUpperBound.setMinimum(self.ui.spinBoxLowerBound.value())
        self.ui.spinBoxBoundaryNumber.setMaximum(math.ceil((self.ui.spinBoxUpperBound.value()
                                                            - self.ui.spinBoxLowerBound.value()) / 2))