g. index type of a <code class="computeroutput"><span class="identifier">Polygon</span></code>
        stored in the vector or an iterator of list of <code class="computeroutput"><span class="identifier">Ring</span></code>s.
        To keep it simple to define <code class="computeroutput"><span class="identifier">Value</span></code>
        we will use predefined Box and unsigned int.
      </p>
<p>
</p>
<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">bg</span><span