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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 service_define(self, service, ty):
 """ Add a service variable of type ``ty`` to this model :param str service: variable name :param type ty: variable type :return: None """


        assert service not in self._data
        assert service not in self._algebs + self._states

        self._service.append(service)
        self._service_ty.append(ty)