kwadraat :: Int -> Int 
kwadraat x = x * x 

kwadr :: Int -> Int 
kwadr = \ x -> x * x 

drievoud :: Int -> Bool
drievoud = \ x -> (rem x 3 == 0)

awoord :: [Char] -> Bool
awoord [] = False 
awoord (x:xs) = (x == 'a') || (awoord xs)