def METHOD_NAME(idx):
    # create a new sample with just a single batch item so that there's
    # no padding
    sample1 = next(test_utils.dummy_dataloader([self.data[idx]]))
    args1 = copy.copy(self.args)
    args1.probs = args1.probs[idx, :, :].unsqueeze(0)
    model1 = self.task.build_model(args1)
    loss1, _, _ = crit(model1, sample1)
    return loss1