">.</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;C&quot;</span><span class="p">]</span>

        <span class="k">if</span> <span class="n">func_groups</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
            <span class="n">func_groups</span> <span class="o">=</span> <span class="p">[</span><span class="s2">&quot;methyl&quot;</span><span class="p">,</spa