"identifier">combine_requirements</span><span class="special">&lt;</span>
            <span class="identifier">sinks</span><span class="special">::</span><span class="identifier">synchronized_feeding</span><span class="special">,</span>
            <span class="identifier">sinks</span><span class="special">::</span><span class="identifier">flushing</span>
        <span class="special">&gt;::</span><span class="identifier">type</span>
    <span class="special">&gt;</span>
<span class="special">{</span>
<span