>zeros</span><span class="p">((</span><span class="n">pad_len</span><span class="p">,</span> <span class="n">xf</span><span class="o">.</span><span class="n">shape</span><span class="p">[</span><span class="mi">1</span><span class="p">]))),</span> <span class="n">axis</span><span class="o">=</span><span class="mi">0</span><span class="p">)</span>
    <span class="k">else</span><span class="p">:</span>
        <span class="n">y</span> <span class="o">=</span> <span class="n">xf</span><span class="p">[</span>