an class="identifier">extract_member</span></code> is a model
          of <a class="link" href="../concepts/extractor.html" title="Extractor"><code class="computeroutput"><span class="identifier">Extractor</span></code></a>
          which can be used in the common case in the common case where the C++ type
          to be extracted is a member of the Python object.
        </p>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{<