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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def model_changed(self, model):
 """Apply the model to the combobox When a level instance is created, the model is None. So it has to be set afterwards. Then this method will be called and your level should somehow use the model :param model: the model that the level should use :type model: QtCore.QAbstractItemModel :returns: None :rtype: None :raises: None """

        self.setModel(model)
        # to update all lists belwo
        # current changed is not triggered by setModel somehow
        if model is not None:
            self.setCurrentIndex(self.model().index(0, 0))