n</h2>
<p>A forward iterator is an iterator that can read through a sequence of
  values.  It is multi-pass (old values of the iterator can be
  re-used), and can be either mutable (data pointed to by it can be
  changed) or not mutable.</p>
<p>An iterator represents a position in a sequence.  Therefore, the
  iterator can point into the sequence (returning a value when dereferenced
  and being incrementable), or be off-the-end (and not dereferenceable or
  incrementable).</p>
</div>
<div class="refsect1">
