an class="o">&gt;</span> <span class="mi">0</span> <span class="ow">and</span> <span class="n">num_surfaces</span> <span class="o">&lt;</span> <span class="mi">2</span><span class="p">:</span>
                    <span class="n">sg</span> <span class="o">=</span> <span class="n">SlabGenerator</span><span class="p">(</span><span class="n">structure</span><span class="p">,</span> <span class="p">(</span><span class="n">h</span><span class="p">,</span> <span class="n">k</span><span class="p">,</span> <span cla