Maybe less intuitive but simpler - can always do the conversion in some </span>
        <span class="c1"># prediction wrapper that doesn&#39;t add computation during training.</span>
<span class="c1">#         return chunk, [0] + list(order) + [mid_len-1]</span>

        <span class="c1"># This version returns the order to map from the permuted indices to the original </span>
        <span class="c1"># indices. Intuitive but adds computation and hard-to-read logic.</span>
<span class="c1">#         return (