libCase env (Type ty) = Type ty
libCase env (App fun arg) = App (libCase env fun) (libCase env arg)
libCase env (Note note body) = Note note (libCase env body)
libCase env (Type ty) = Type ty
libCase env (App fun arg) = App (libCase env fun) (libCase env arg)
libCase env (Note note body) = Note note (libCase env body)