rased from the intrusive container, the
            container puts the erased object in the well-known default state.
          </li>
</ul></div>
<p>
        With these features, without any external reference the user can know if
        the object has been inserted in a container by calling the <code class="computeroutput"><span class="identifier">is_linked</span><span class="special">()</span></code>
        member function. If the object is not actually inserted in a container, the
        hook is in th