splitL :: (Sized a) => Node a -> Breadth -> (Node a, Node a)
splitL (Node s n) b =
  case splitNode n (V.length n - b) of
    (l, d) -> (node l, node (V.force d))
splitL :: (Sized a) => Node a -> Breadth -> (Node a, Node a)
splitL (Node s n) b =
  case splitNode n (V.length n - b) of
    (l, d) -> (node l, node (V.force d))
splitL (Node s n) b =
  case splitNode n (V.length n - b) of
    (l, d) -> (node l, node (V.force d))