 class="p">,</span> <span class="n">VertexSeq</span><span class="p">):</span>
                    <span class="n">group</span> <span class="o">=</span> <span class="p">[</span><span class="n">vertex</span><span class="o">.</span><span class="n">index</span> <span class="k">for</span> <span class="n">vertex</span> <span class="ow">in</span> <span class="n">group</span><span class="p">]</span>
                <span class="k">if</span> <span class="ow">not</span> <span class="nb">hasattr</span><span class="p">