<span class="n">c</span><span class="p">,</span> <span class="n">system</span><span class="p">,</span> <span class="n">centers</span><span class="p">,</span> <span class="n">indices</span><span class="p">,</span> <span class="n">attach</span><span class="p">,</span> <span class="n">return_descriptor</span>
            <span class="p">)</span>
        <span class="k">elif</span> <span class="n">method</span> <span class="o">==</span> <span class="s2">&quot;analytical&quot;</span><span class="p">:</span>
    