<a href="#exception-Invalid_state" class="anchor"></a><code><span><span class="keyword">exception</span> </span><span><span class="exception">Invalid_state</span> <span class="keyword">of</span> <a href="#type-state">state</a></span></code></div></div><div class="odoc-spec"><div class="spec value anchored" id="val-add_transition"><a href="#val-add_transition" class="anchor"></a><code><span><span class="keyword">val</span> add_transition : <span><span>(<a href="#type-state">state</a> * <a href="#type-label">