snoc :: (Sized a) => Node a -> a -> Node a
snoc (Node s n) a = Node (size a + s) (V.snoc n a)
snoc :: (Sized a) => Node a -> a -> Node a
snoc (Node s n) a = Node (size a + s) (V.snoc n a)
snoc (Node s n) a = Node (size a + s) (V.snoc n a)