 are determined
   to have different lengths.</p>
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<pre><span id="VALmem"><span class="keyword">val</span> mem</span> : <code class="type">'a -&gt; 'a list -&gt; bool</code></pre><div class="info ">
<div class="info-desc">
<p><code class="code">mem&nbsp;a&nbsp;l</code> is true if and only if <code class="code">a</code> is equal
   to an element of <code class="code">l</code>.</p>
</div>
</div>

<pre><span id="VALmemq"><span class="keyword">val</span> memq</span> : <code class="type">'a -&gt; '