shrink ut@(Data.Time.UTCTime day dayTime) =
        [ ut { Data.Time.utctDay     = d' } | d' <- shrink day     ] ++
        [ ut { Data.Time.utctDayTime = t' } | t' <- shrink dayTime ]
shrink ut@(Data.Time.UTCTime day dayTime) =
        [ ut { Data.Time.utctDay     = d' } | d' <- shrink day     ] ++
        [ ut { Data.Time.utctDayTime = t' } | t' <- shrink dayTime ]
shrink ut@(Data.Time.UTCTime day dayTime) =
        [ ut { Data.Time.utctDay     = d' } | d' <- shrink day     ] ++
        [ ut { Data.Time.utctDayTime = t' } | t' <- shrink dayTime ]