 class="n">default</span><span class="o">=</span><span class="s2">&quot;mean&quot;</span><span class="p">,</span> <span class="n">metadata</span><span class="o">=</span><span class="p">{</span><span class="s2">&quot;help&quot;</span><span class="p">:</span> <span class="s2">&quot;Reduction method of criterion&quot;</span><span class="p">}</span>
    <span class="p">)</span>
    <span class="n">gather</span><span class="p">:</span> <span class="nb">bool</span> <span class="o">=</span> <span class="n">field</