dule-Lock" class="anchor"></a><code><span><span class="keyword">module</span> <a href="Lock/index.html">Lock</a></span><span> : <span class="keyword">sig</span> ... <span class="keyword">end</span></span></code></div><div class="spec-doc"><p>Abstract address for a lock. There are two notions of equality:</p></div></div><div class="odoc-spec"><div class="spec module" id="module-VarDomain" class="anchored"><a href="#module-VarDomain" class="anchor"></a><code><span><span class="keyword">module</span> <a href="