pan> <span class="n">Stock_Extractor</span><span class="p">(</span><span class="n">stockSymbol</span><span class="p">,</span><span class="n">source</span><span class="p">)</span>
        <span class="n">data</span> <span class="o">=</span> <span class="n">se</span><span class="o">.</span><span class="n">get_stock_period</span><span class="p">(</span><span class="n">periods</span><span class="p">)</span>
        <span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span cla