ef="../iterator_facade.html" target="_top">facade</a> class template,
      which implements many useful defaults and compile-time checks designed to help
      the iterator author ensure that his iterator is correct.
    </p>
<p>
      It is also common to define a new iterator that is similar to some underlying
      iterator or iterator-like type, but that modifies some aspect of the underlying
      type's behavior. For that purpose, the library supplies the <a href="../iterator_adaptor.html" target="_t