The case you're looking for would look something like this:

for i in xrange(30):
    if features.caughtBall:
        yield 'stand'
        break
    else:
        yield command

I don't have an example of "real" code to show yet. As I said above, I've not started to try reimplementing all our old behaviors in the new system, but there's no technical reason why this approach won't work. Perhaps I'll make another post when I have something more complex ready.