This wasn't fully implemented, and I don't actually think there's a
real reason for it to exist. It was cargo culted over from my own
thinking about click functionality, but API differences mean it just
isn't really useful here.
the checklist of things to do is continuing to dwindle. hooray. last
big feature push is help text generation. Then improving error
reporting. Then writing some tests. Then writing documentation.
Ay carumba.