use keysSet to turn IdMap's to IdSet's.
use keysSet to turn IdMap's to IdSet's.

darcs-hash:20080222125426-1a7c6-b5a8ca64e521f446ca22c19eb164d08545661ac9

jimcrayne/jhc,jimcrayne/jhc,jimcrayne/jhc,jimcrayne/jhc