ude"><code><span><span class="keyword">include</span> <a href="../../NS/Invariant/module-type-S/index.html">NS.Invariant.S</a> <span class="keyword">with</span> <span><span class="keyword">type</span> <a href="../../NS/Invariant/module-type-S/index.html#type-t">t</a> := <a href="#type-t">t</a></span></span></code></summary><div class="odoc-spec"><div class="spec value anchored" id="val-invariant"><a href="#val-invariant" class="anchor"></a><code><span><span class="keyword">val</span> invariant : <span><a hr