<span class="identifier">Backend</span><span class="special">&gt;&amp;</span> <span class="identifier">b</span><span class="special">)</span>
<span class="special">{</span>
   <span class="identifier">number</span><span class="special">&lt;</span><span class="identifier">Backend</span><span class="special">&gt;</span> <span class="identifier">result</span><span class="special">(</span><span class="identifier">a</span><span class="special">);</span>
   <span class="identifier">result</span> <span class="spec