lass="code">s</code> after position <code class="code">i</code>.  <code class="code"><span class="constructor">Bytes</span>.index&nbsp;s&nbsp;c</code> is
    equivalent to <code class="code"><span class="constructor">Bytes</span>.index_from&nbsp;s&nbsp;0&nbsp;c</code>.</p>

<p>Raise <code class="code"><span class="constructor">Invalid_argument</span></code> if <code class="code">i</code> is not a valid position in <code class="code">s</code>.
    Raise <code class="code"><span class="constructor">Not_found<