</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> <a href="index.html#type-t">t</a></span></code></dt><dt class="spec value" id="val-update"><a href="#val-update" class="anchor"></a><code><span class="keyword">val</span> update : <a href="index.html#type-key">key</a> <span>&#45;&gt;</span> <span>(<span><span class="type-var">'a</span> option</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</span> option</span>)</span> <span>&#45;&gt;</span> <span><span class="type-var">'a</s