/span></span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-merge"><a href="#val-merge" class="anchor"></a><code><span><span class="keyword">val</span> merge : 
  <span><span>(<span><a href="#type-key">key</a> <span class="arrow">&#45;&gt;</span></span> <span><span><span class="type-var">'a</span> option</span> <span class="arrow">&#45;&gt;</span></span> <span><span><span class="type-var">'b</span> option</span> <span class="arrow">&#45;&gt;</span></span> <span><span clas