averse
  :: Applicative h
  => (forall x. f x -> h (g x))
  -> Rec f rs
  -> h (Rec g rs)
rtraverse _ RNil      = pure RNil
rt
rtraverse
  :: Applicative h
  => (forall x. f x -> h (g x))
  -> Rec f rs
  -> h (Rec g rs)
rtraverse _ RNil      = pure RNil
rtraverse _ RNil      = pure RNil