!r</code> returns the current contents of reference <code class="code">r</code>.
   Equivalent to <code class="code"><span class="keyword">fun</span> r <span class="keywordsign">-&gt;</span> r.contents</code>.<br>
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<pre><span id="VAL(:=)"><span class="keyword">val</span> (:=)</span> : <code class="type">'a <a href="Pervasives.html#TYPEref">ref</a> -&gt; 'a -&gt; unit</code></pre><div class="info ">
<code class="code">r := a</code> stores the value of <code class="code">a</code> in reference <code cla