e">rindex_from_opt&nbsp;s&nbsp;i&nbsp;c</code> is the index of the last occurrence of <code class="code">c</code>
    in <code class="code">s</code> before position <code class="code">i+1</code> (if any).</p>
</div>
<ul class="info-attributes">
<li><b>Since</b> 4.05</li>
<li><b>Raises</b> <code>Invalid_argument</code> if <code class="code">i+1</code> is not a valid position in <code class="code">s</code>.</li>
</ul>
</div>

<pre><span id="VALindex"><span class="keyword">val</span> index</span> : <code class