><code><span class="keyword">val</span> check : <a href="index.html#type-type_role">type_role</a> <span>&#45;&gt;</span> <span>base:<a href="../Nullability/index.html#type-t">Nullability.t</a></span> <span>&#45;&gt;</span> <span>overridden:<a href="../Nullability/index.html#type-t">Nullability.t</a></span> <span>&#45;&gt;</span> <span><span>(unit, <a href="index.html#type-violation">violation</a>)</span> <a href="../../IStdlib/index.html#module-IStd">IStdlib.IStd</a>.result</span></code></dt><dd><p>See des