warning</span><span class="special">);</span>
    <span class="identifier">sink</span><span class="special">-&gt;</span><span class="identifier">set_formatter</span>
    <span class="special">(</span>
        <span class="identifier">expr</span><span class="special">::</span><span class="identifier">stream</span>
            <span class="special">&lt;&lt;</span> <span class="string">"Level: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">expr</span><span class="special">::</span><spa