el of user-level functions</p></li>
</ul></div>
    <div id="see-also">
    <h2>See also</h2>
    <div class="dont-index"><p>For general argument checking, see <code><a href="check_arg.html">check_arg()</a></code> and <code><a href="check_arg.html">check_set_arg()</a></code>.</p></div>
    </div>
    <div id="author">
    <h2>Author</h2>
    <p>Laurent Berge</p>
    </div>

    <div id="ref-examples">
    <h2>Examples</h2>
    <div class="sourceCode"><pre class="sourceCode r"><code><span class="r-in"><span>