ator to hold the state information
        required to serialize the trailer:
      </p>
<pre class="programlisting"><span class="comment">// Prepare a chunked HTTP/1.1 response with some trailer fields</span>
<span class="identifier">response</span><span class="special">&lt;</span><span class="identifier">empty_body</span><span class="special">&gt;</span> <span class="identifier">res</span><span class="special">{</span><span class="identifier">status</span><span class="special">::</span><span class="identi