<code>Set</code> and <code>FALSE</code>
otherwise.</p></li>
</ul><ul><li><p><code>is.orderedset(x)</code> returns <code>TRUE</code> if <code>x</code> is of class <code>OrderedSet</code>
and <code>FALSE</code> otherwise.</p></li>
</ul><ul><li><p><code>x</code> <code>&amp;</code> <code>y</code> performs the set intersection of x and y</p></li>
</ul><ul><li><p><code>x</code> <code>|</code> <code>y</code> performs the set union of x and y</p></li>
</ul></div>
    <div class="section level2">
    <h2 id="see-als