n class="identifier">iterator_adaptor</span></code>.
          In particular, have a look at |transform_iterator|<span class="underline">,
          which is perhaps the most straightforward adaptor, and also |counting_iterator|</span>,
          which demonstrates that <code class="computeroutput"><span class="identifier">iterator_adaptor</span></code>'s
          <code class="computeroutput"><span class="identifier">Base</span></code> type needn't be an
          iterator.
        </p>
<p>
          .. |r