 real-world scenarios, which show that the exit action to destructor mapping
  <b>can</b> be a problem and that workarounds are overly cumbersome. That's
  why <a href="tutorial.html#TwoStageExit">two stage exit</a> is now
  supported.</p>

  <h2><a name="AsynchronousStateMachines" id=
  "AsynchronousStateMachines">Asynchronous state machines</a></h2>

  <h3>Requirements</h3>

  <p>For asynchronous state machines different applications have rather
  varied requirements:</p>

  <ol>
    <li>In some applicati