an><span class="o">.</span><span class="n">molgraph</span><span class="o">.</span><span class="n">graph</span><span class="o">.</span><span class="n">nodes</span> <span class="k">if</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="o">==</span> <span class="s2">&quot;H&quot;</span><span class="p">}</span>

      