t; which includes the keys <code>base</code>
and <code>extent</code> indicating where the selection within the <code>value</code> of the
semantics node should start and where it should end. Values for both
keys can range from 0 to length of <code>value</code> (inclusive).</p>
<p>Setting <code>base</code> and <code>extent</code> to the same value will move the cursor to
that position (without selecting anything).</p>
    </section>
        <section class="summary source-code" id="source">
      <h2><span>Imp