> <span class="identifier">x3</span><span class="special">::</span><span class="identifier">lexeme</span><span class="special">;</span>
    <span class="keyword">using</span> <span class="identifier">ascii</span><span class="special">::</span><span class="identifier">char_</span><span class="special">;</span>

    <span class="identifier">x3</span><span class="special">::</span><span class="identifier">rule</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">em