o propose an anchor point for the label</span>
                <span class="n">src</span><span class="p">,</span> <span class="n">dest</span> <span class="o">=</span> <span class="n">edge</span><span class="o">.</span><span class="n">tuple</span>
                <span class="n">src_vertex</span><span class="p">,</span> <span class="n">dest_vertex</span> <span class="o">=</span> <span class="n">vertex_builder</span><span class="p">[</span><span class="n">src</span><span class="p">],</span> <span class="n">ve