n><span class="p">[</span><span class="n">u</span><span class="p">]</span> <span class="o">&lt;</span> <span class="bp">self</span><span class="o">.</span><span class="n">f</span><span class="p">[</span><span class="n">v</span><span class="p">]:</span>
            <span class="n">lowerVertex</span> <span class="o">=</span> <span class="n">u</span>
        <span class="k">else</span><span class="p">:</span>
            <span class="n">lowerVertex</span> <span class="o">=</span> <span class="n">v</span>

    