 class="keyword">inline</span> <span class="special">&lt;</span><span class="identifier">unspecified</span><span class="special">&gt;</span>
    <span class="identifier">format_delimited</span><span class="special">(</span>
        <span class="identifier">Attr</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">attr</span>
      <span class="special">,</span> <span class="identifier">Delimiter</span> <span class="keyword">const</span><span class="special">&a