parse.
          </li>
</ul></div>
<p>
        By subclassing the rule class from a client supplied handler such as our
        <code class="computeroutput"><span class="identifier">annotate_position</span></code> handler
        above:
      </p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">person_class</span> <span class="special">:</span> <span class="identifier">annotate_position</span> <span class="special">{};</span>
<span class="keyword">struct</span> <span