an class="o">=</span><span class="n">sample_size</span><span class="p">)</span>
        <span class="c1"># Generate copies of the query instance that will be changed one feature</span>
        <span class="c1"># at a time to encourage sparsity.</span>
        <span class="n">cfs_df</span> <span class="o">=</span> <span class="kc">None</span>
        <span class="n">candidate_cfs</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">DataFrame</span><span class="p">(