meet the full requirements for an iterator; it need only support
        the operations used by the core interface functions of <code class="computeroutput"><span class="identifier">iterator_adaptor</span></code>
        that have not been redefined in the user's derived class.
      </p>
<p>
        Several of the template parameters of <code class="computeroutput"><span class="identifier">iterator_adaptor</span></code>
        default to <code class="computeroutput"><span class="identifier">use_default</s