pan class="n">f</span>
                    <span class="n">df</span><span class="o">.</span><span class="n">loc</span><span class="p">[</span><span class="n">substring</span><span class="p">,</span> <span class="s2">&quot;has_been_evaluated&quot;</span><span class="p">]</span> <span class="o">=</span> <span class="kc">True</span>

    <span class="n">srs</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">Series</span><span class="p">(</span><span class="nb">map<