throw new JellyException( "Unable to locate a transition." );
return;
    public void doTag(final XMLOutput output) throws Exception    {        TransitionTag transitionTag = (TransitionTag) findAncestorWithClass( TransitionTag.class );        if ( transitionTag == null )        {            throw new JellyException( "Unable to locate a transition." );        }        Transition transition = transitionTag.getTransition();        if ( transition.getGuard() != null )        {            throw new JellyException( "Guard already defined for transition" );        }        final Script script = getBody();                Guard guard = new Guard()            {                public boolean test(Transition transition,                                    ProcessContext procession)                 {                    try                    {                        script.run( getContext(),                                    output );                    }                    catch (PassException e)                    {                        return true;                    }                    catch (FailException e)                    {                        return false;                    }                    catch (JellyException e)                    {                        return false;                    }                    catch (Exception e)                    {                        return false;                    }                    return true;                }            };                transition.setGuard( guard );    }