addTick :: Maybe (Bool -> BoxLabel) -> LHsExpr Id -> TM (LHsExpr Id)
addTick isGuard e | Just fn <- isGuard = addBinTickLHsExpr fn e
                  | otherwise          = addTickLHsExprRHS e
addTick :: Maybe (Bool -> BoxLabel) -> LHsExpr Id -> TM (LHsExpr Id)
addTick isGuard e | Just fn <- isGuard = addBinTickLHsExpr fn e
                  | otherwise          = addTickLHsExprRHS e
addTick isGuard e | Just fn <- isGuard = addBinTickLHsExpr fn e
                  | otherwise          = addTickLHsExprRHS e