ref="#sample_prices-17"><span class="linenos">17</span></a>
</span><span id="sample_prices-18"><a href="#sample_prices-18"><span class="linenos">18</span></a>    <span class="k">if</span> <span class="n">freq</span> <span class="ow">not</span> <span class="ow">in</span> <span class="n">FREQUENCIES</span><span class="p">:</span>
</span><span id="sample_prices-19"><a href="#sample_prices-19"><span class="linenos">19</span></a>        <span class="k">raise</span> <span class="ne">ValueError</span><span class="