h</span><span class=special>&lt;</span><span class=identifier>nil_t</span><span class=special>&gt;
        </span><span class=identifier>empty_match</span><span class=special>() </span><span class=keyword>const
        </span><span class=special>{ </span><span class=keyword>
            return </span><span class=identifier>match</span><span class=special>&lt;</span><span class=identifier>nil_t</span><span class=special>&gt;(</span><span class=number>0</span><span class=special>, </span><span class=identifie