span> <span class="n">node</span><span class="p">)</span>
                    <span class="n">neighbor_spec</span> <span class="o">=</span> <span class="nb">sorted</span><span class="p">([</span><span class="nb">str</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">species</span><span class="p">[</span><span class="n">n</span><span class="p">[</span><span class="s2">&quot;site_index&quot;</span><span class="p">]])</span>
                                       