úÎÎ     (c) Fumiaki Kinoshita 2014 BSD3 (Fumiaki Kinoshita <fumiexcel@gmail.com>  experimental  non-portable None&(1234=HJKM        elevator-0.1.3Control.ElevatorElevateTowerFloorsFloors1toLofttoLoft1elevate$fTowerExceptT $fTowerListT $fTowerMaybeT $fTowerContT$fTowerWriterT$fTowerWriterT0$fTowerReaderT $fTowerStateT$fTowerStateT0 $fTowerUnion $fTowerST $fTower[] $fTower(->) $fTowerEither $fTowerMaybe$fTowerIdentity $fTowerIO