  <span class="keyword">namespace</span> <span class="identifier">qi</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">spirit</span><span class="special">::</span><span class="identifier">qi</span><span class="special">;</span>

    <span class="comment">// A plain function</span>
    <span class="keyword">void</span> <span class="identifier">print</span><span class="special">(</span><span class="keyword">int</span> <span class