an class="comment">// Manually emit a trailer.</span>
<span class="comment">// We are responsible for ensuring that the trailer format adheres to the specification.</span>
<span class="identifier">string_view</span> <span class="identifier">ext</span> <span class="special">=</span>
    <span class="string">"Content-MD5: f4a5c16584f03d90\r\n"</span>
    <span class="string">"Expires: never\r\n"</span>
    <span class="string">"\r\n"</span><span class="special">;</span>
<span class="identifier">boost</span><s