lass="n">py</span><span class="o">.</span><span class="n">item</span><span class="p">)</span>
        <span class="n">prev</span> <span class="o">=</span> <span class="mi">0</span>
        <span class="k">for</span> <span class="n">ex</span> <span class="ow">in</span> <span class="n">px</span><span class="o">.</span><span class="n">elements</span><span class="p">:</span>
            <span class="n">ey</span> <span class="o">=</span> <span class="bp">self</span><span class="o">.</span><span class="n">_findEl