span>
        <span class="k">for</span> <span class="n">vertex</span> <span class="ow">in</span> <span class="bp">self</span><span class="o">.</span><span class="n">vertices</span><span class="p">:</span>
            <span class="n">label</span> <span class="o">=</span> <span class="n">vertex</span><span class="o">.</span><span class="n">getLabel</span><span class="p">()</span>
            <span class="k">if</span> <span class="n">label</span> <span class="ow">not</span> <span class="ow">in</span> <span cl