s="n">atom_cluster</span><span class="p">:</span>
            <span class="k">if</span> <span class="ow">not</span> <span class="n">visited</span><span class="p">[</span><span class="n">new_atom</span><span class="p">]:</span>
                <span class="n">visited</span><span class="p">[</span><span class="n">new_atom</span><span class="p">]</span> <span class="o">=</span> <span class="kc">True</span>
                <span class="n">atom_cluster</span> <span class="o">=</span> <span class="n">visit</span>