l">&lt;</span><span class="identifier">Tail</span><span class="special">&gt;::</span><span class="identifier">type</span>
<span class="identifier">distinct_spec</span><span class="special">(</span><span class="identifier">Tail</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">tail</span><span class="special">)</span>
<span class="special">{</span>
    <span class="keyword">return</span> <span class="identifier">repo</span><span class="special">::</span><spa