pecial">&lt;</span><span class="identifier">safe_link</span><span class="special">&gt;</span> <span class="special">&gt;</span>
<span class="special">{};</span>
</pre>
<p>
        With the safe mode the user can detect if the object is actually inserted
        in a container without any external reference. Let's review the basic features
        of the safe mode:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem">
            Hook's constructor puts the hook in 