/span><span class="p">():</span>
                <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">x</span><span class="p">)</span> <span class="o">==</span> <span class="mi">1</span><span class="p">:</span>
                    <span class="n">periods</span><span class="p">[</span><span class="n">x</span><span class="p">]</span> <span class="o">=</span> <span class="n">y</span>
                <span class="k">else</span><span class="p">:</span>
                    