el of <a class="link" href="../../../sequence/concepts/forward_sequence.html" title="Forward Sequence">Forward
                Sequence</a>.
              </li>
<li class="listitem">
                A model of <a class="link" href="../../../sequence/concepts/associative_sequence.html" title="Associative Sequence">Associative
                Sequence</a> if <code class="computeroutput"><span class="identifier">Sequence</span></code>
                implements the <a class="link" href="../../../sequence/conce