/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-remove_state"><a href="#val-remove_state" class="anchor"></a><code><span><span class="keyword">val</span> remove_state : <span><a href="#type-state">state</a> <span class="arrow">&#45;&gt;</span></span> <span><a href="#type-t">t</a> <span class="a