er">rule</span><span class="special">&lt;</span><span class="identifier">quoted_string_class</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span><span class="special">&gt;</span> <span class="keyword">const</span> <span class="identifier">quoted_string</span> <span class="special">=</span> <span class="string">"quoted_string"</span><span class="special">;</span>
    <span class="identifier">x3</span><span class="special