l</span> <span class="o">=</span> <span class="n">token2label</span>

    <span class="k">def</span> <span class="fm">__len__</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span> <span class="o">-&gt;</span> <span class="nb">int</span><span class="p">:</span>
        <span class="sd">&quot;&quot;&quot;Returns the number of molecules in the dataset.</span>

<span class="sd">        Returns</span>
<span class="sd">        -------</span>
<span class="sd">        int</span>
<span c