= WwLazy -- Argument is lazy as far as we know
MaybeAbsent -- (does not imply worker's existence [etc]).
-- If MaybeAbsent == True, then it is
= WwLazy -- Argument is lazy as far as we know
MaybeAbsent -- (does not imply worker's existence [etc]).
-- If MaybeAbsent == True, then it is