span class="n">l0</span> <span class="o">!=</span> <span class="n">l1</span><span class="p">:</span>  <span class="c1"># verifies the two arrays are the same length</span>
        <span class="c1"># removes last element from x1 to make l1 and l0 the same size</span>
        <span class="n">z1</span> <span class="o">=</span> <span class="n">z1</span><span class="p">[:</span><span class="o">-</span><span class="mi">1</span><span class="p">]</span>

    <span class="n">z_diff</span> <span class="o">=</span> <s