def METHOD_NAME(i, loss_sum):
    rng_key_binarize = random.fold_in(rng_key, i)
    batch = binarize(rng_key_binarize, test_fetch(i, test_idx)[0])
    # FIXME: does this lead to a requirement for an rng_key arg in svi_eval?
    loss = svi.evaluate(svi_state, batch) / len(batch)
    loss_sum += loss
    return loss_sum