Function to tell if text is in choice mode or output mode

Would be useful in some circs to be able to say test "is the current text part of a choice, or part of the weave output of a choice."

eg.

* I {CHOICE_TEXT():reached|tried to reach} for the gun[] but I wasn't fast enough.

(My main complaint here is that this isn't very elegant, but I'm not sure it's worth a whole syntax for. )