an><span class="p">:</span> <span class="nb">str</span> <span class="o">=</span> <span class="kc">None</span><span class="p">):</span>
</span><span id="L-15"><a href="#L-15"><span class="linenos">15</span></a><span class="w">    </span><span class="sd">&quot;&quot;&quot;Sample prices&quot;&quot;&quot;</span>
</span><span id="L-16"><a href="#L-16"><span class="linenos">16</span></a>
</span><span id="L-17"><a href="#L-17"><span class="linenos">17</span></a>    <span class="k">if</span> <span class="n">freq</s