hoistUnion :: (f a -> g a) -> Union (f ': fs) a -> Union (g ': fs) a
hoistUnion f (Here e) = Here (f e)
hoistUnion :: (f a -> g a) -> Union (f ': fs) a -> Union (g ': fs) a
hoistUnion f (Here e) = Here (f e)
hoistUnion f (Here e) = Here (f e)