How to use the skorch.utils.FirstStepAccumulator function in skorch

def get_train_step_accumulator(self):
        """Return the train step accumulator.

        By default, the accumulator stores and retrieves the first
        value from the optimizer call. Most optimizers make only one
        call, so first value is at the same time the only value.

        In case of some optimizers, e.g. LBFGS,
        ``train_step_calc_gradient`` is called multiple times, as the
        loss function is evaluated multiple times per optimizer
        call. If you don't want to return the first value in that
        case, override this method to return your custom accumulator.

        """
        return FirstStepAccumulator()

def get_train_step_accumulator(self):
        """Return the train step accumulator.

        By default, the accumulator stores and retrieves the first
        value from the optimizer call. Most optimizers make only one
        call, so first value is at the same time the only value.

        In case of some optimizers, e.g. LBFGS,
        ``train_step_calc_gradient`` is called multiple times, as the
        loss function is evaluated multiple times per optimizer
        call. If you don't want to return the first value in that
        case, override this method to return your custom accumulator.

        """
        return FirstStepAccumulator()