instance Umai () where {}
newtype X10 a = X10 a
nasu = X10 (X10 ())

class Oldtype a where { oldtype :: a b -> b }
instance Oldtype X10 where { oldtype (X10 o) = o }
instance Umai a => Umai (X10 a) where { level x = level (oldtype x) * 10 }