ref="index.html#type-t">t</a> <span>&#45;&gt;</span> <a href="index.html#type-elt">elt</a></code></dt><dt class="spec value" id="val-choose_opt"><a href="#val-choose_opt" class="anchor"></a><code><span class="keyword">val</span> choose_opt : <a href="index.html#type-t">t</a> <span>&#45;&gt;</span> <span><a href="index.html#type-elt">elt</a> option</span></code></dt><dt class="spec value" id="val-split"><a href="#val-split" class="anchor"></a><code><span class="keyword">val</span> split : <a href="index.html