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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 set_model(self, m):
 """Set the model for the level :param m: the model that the level should use :type m: QtCore.QAbstractItemModel :returns: None :rtype: None :raises: None """

        self._model = m
        self.new_root.emit(QtCore.QModelIndex())
        self.model_changed(m)