>
   if <code class="code">(a,b)</code> is the leftmost binding of <code class="code">a</code> in list <code class="code">l</code>.
   Raise <code class="code"><span class="constructor">Not_found</span></code> if there is no value associated with <code class="code">a</code> in the
   list <code class="code">l</code>.</p>
</div>
</div>

<pre><span id="VALassoc_opt"><span class="keyword">val</span> assoc_opt</span> : <code class="type">'a -&gt; ('a * 'b) list -&gt; 'b option</code></pre><div class="info ">
<d