#t29">29</a></span><span class="t">        <span class="nam">loss</span><span class="op">.</span><span class="nam">backward</span><span class="op">(</span><span class="op">)</span>&nbsp;</span><span class="r"></span></p>
    <p class="run"><span class="n"><a id="t30" href="#t30">30</a></span><span class="t">        <span class="key">return</span> <span class="nam">batch_weight</span><span class="op">.</span><span class="nam">detach</span><span class="op">(</span><span class="op">)</span><span class="op">.</