de">const_iterator</code>
    typedef from the sequence type this iterator can reference.</p></li><li class="listitem"><p><code class="code">Sequence</code>: The type of sequence that this iterator
  references. This sequence must be a safe sequence (discussed below)
  whose <code class="code">iterator</code> or <code class="code">const_iterator</code> typedef
  is the type of the safe iterator.</p></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h5 class="title"><a id="debug_mod