="n">symbols</span> <span class="o">=</span> <span class="n">system</span><span class="o">.</span><span class="n">get_chemical_symbols</span><span class="p">()</span>
        <span class="n">unique</span><span class="p">,</span> <span class="n">counts</span> <span class="o">=</span> <span class="n">np</span><span class="o">.</span><span class="n">unique</span><span class="p">(</span><span class="n">symbols</span><span class="p">,</span> <span class="n">return_counts</span><span class="o">=</span><span class