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> <span><span>(<a href="#type-state">state</a> * <a href="#type-label">label</a>)</span> list</span></span></code></div><div class="spec-doc"><p><code>preds' s q</code> returns the list of immediate predecessors, with the associated transition label, of state <code>q</code> in <code>s</code>. Raise Invalid_arg