eyword">sig</span> ... <span class="keyword">end</span></code></div><div class="spec module" id="module-Optgroup"><a href="#module-Optgroup" class="anchor"></a><code><span class="keyword">module </span><a href="Optgroup">Optgroup</a> : <span class="keyword">sig</span> ... <span class="keyword">end</span></code></div><div class="spec module" id="module-Option"><a href="#module-Option" class="anchor"></a><code><span class="keyword">module </span><a href="Option">Option</a> : <span class="keyword">sig</span> .