> <span class="identifier">argument_type</span> <span class="special">;</span>

    <span class="keyword">static</span> <span class="identifier">result_type</span> <span class="identifier">low_level_convert</span> <span class="special">(</span> <span class="identifier">argument_type</span> <span class="identifier">s</span> <span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="special">&lt;</span><span class="identifier">impl</span> <span class="identi