tail :: (Sized a) => Node a -> Node a
tail (Node s n) = Node (s - size (V.head n)) (V.force (V.tail n))
tail :: (Sized a) => Node a -> Node a
tail (Node s n) = Node (s - size (V.head n)) (V.force (V.tail n))
tail (Node s n) = Node (s - size (V.head n)) (V.force (V.tail n))