<span class="n">symmetric</span> <span class="ow">and</span> <span class="n">j</span> <span class="o">==</span> <span class="n">i</span><span class="p">:</span>
                    <span class="n">y_j</span> <span class="o">=</span> <span class="kc">None</span>
                <span class="k">else</span><span class="p">:</span>
                    <span class="n">y_j</span> <span class="o">=</span> <span class="n">y</span><span class="p">[</span><span class="n">j</span><span class="p">]</span>
             