de> in <code>s</code>. Raise Invalid_argument if <code>q</code> is not in <code>s</code>.</p></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-preds"><a href="#val-preds" class="anchor"></a><code><span><span class="keyword">val</span> preds : <span><a href="#type-t">t</a> <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-state">state</a> <span class="arrow">&#45;&gt;</span></span> <a href="States/index.html#type-t">States.t</a></span></code></div><div class="spec-doc