def get_fixed_var_descr(self, model, data):
        data_specs = self.get_data_specs(model)
        data_specs[0].validate(data)
        composite_specs, mapping = self.get_composite_specs_and_mapping(model)
        nested_data = mapping.nest(data)

        descrs = [cost.get_fixed_var_descr(model, cost_data)
                  for cost, cost_data in safe_zip(self.costs, nested_data)]

        return reduce(merge, descrs)
.. todo::
dataset/ETHPy150Open lisa-lab/pylearn2/pylearn2/costs/cost.py/SumOfCosts.get_fixed_var_descr