def METHOD_NAME(self):
    """Return an ordered list of indices. Batches will be constructed based
    on this order."""
    if self.shuffle:
        order = [np.random.permutation(len(self))]
    else:
        order = [np.arange(len(self))]
    if self.sort_by_length:
        order.append(self.sizes)
        return np.lexsort(order)[::-1]
    else:
        return order[0]