--- group :: PositiveT n => n -> TFVec s a -> TFVec (Div s n) (TFVec n a)
--- group n = liftV (group' (fromIntegerT n))
--- where group' :: Int -> [a] -> [TFVec s a]
--- group' n xs = case splitAtM n xs of
--- Nothing -> []
--- Just (ls, rs) -> TFVec ls : group' n rs
-