an class="n">nu</span>

    <span class="k">def</span> <span class="fm">__call__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">dgm</span><span class="p">):</span>
        <span class="k">if</span> <span class="nb">len</span><span class="p">(</span><span class="n">dgm</span><span class="p">)</span> <span class="o">==</span> <span class="mi">0</span><span class="p">:</span>
            <span class="k">return</span> <span class="n">dgm</span>

        <span 