routput"><span class="identifier">typeof</span></code>
        it is necessary to register all the types used. For the case of natural numbers,
        this would amount to something like the following:
      </p>
<pre class="programlisting"><span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier">natural</span><span class="special">);</span>
<span class="identifier">BOOST_TYPEOF_REGISTER_TYPE</span><span class="special">(</span><span class="identifier