      <span class="identifier">symbols</span><span class="special">&lt;</span><span class="keyword">unsigned</span><span class="special">&gt;</span> <span class="identifier">tens</span><span class="special">;</span>
        <span class="identifier">symbols</span><span class="special">&lt;</span><span class="keyword">unsigned</span><span class="special">&gt;</span> <span class="identifier">ones</span><span class="special">;</span>

        <span class="identifier">rule</span><span class="special">&lt;</span>