/span><span class="p">(</span><span class="bp">cls</span><span class="p">)</span>
            <span class="k">return</span> <span class="bp">cls</span>

        <span class="k">def</span> <span class="nf">register</span><span class="p">(</span><span class="bp">cls</span><span class="p">,</span> <span class="n">subclass</span><span class="p">):</span>
            <span class="sd">&quot;&quot;&quot;Register a virtual subclass of an ABC.</span>

<span class="sd">            Returns the subclass, to allow usage