(((name . "wb-tree-node?")
  (signature lambda (x) => boolean?)
  (desc "Returns true if `x` is a node in a weight-balanced tree."))
 ((name . "non-null-wb-tree-node?")
  (signature lambda (x) => boolean?)
  (desc "Returns true if `x` is a node with data and children."))
 ((name . "get-data")
  (signature lambda ((non-null-wb-tree-node? x)) => *)
  (desc "Returns the data in the tree node."))
 ((name . "get-left")
  (signature lambda ((non-null-wb-tree-node? x)) => wb-tree-node?)
  (desc "Returns the left child in the node."))
 ((name . "get-right")
  (signature lambda ((non-null-wb-tree-node? x)) => wb-tree-node?)
  (desc "Returns the right child in the node."))
 ((name . "get-size")
  (signature lambda ((wb-tree-node? x)) => integer?)
  (desc "Returns the number of elements in this tree."))
 ((name . "balanced?")
  (signature lambda ((wb-tree-node? x)) => boolean?)
  (desc "Recursively traverses `x` and checks if it is weight balanced."))
 ((name . "in-order-vector->node")
  (signature lambda ((vector? x)) => wb-tree-node?)
  (desc "
* It is an error if `x` is not in order.

Returns a weight-balanced tree where the elements of the tree are the
elements of `x`."))
 ((name . "node->in-order-list")
  (signature lambda ((wb-tree-node? x)) => list?)
  (desc "Returns a list of all elements of `x` in order."))
 ((name . "join")
  (signature lambda (data (wb-tree-node? left) (wb-tree-node? right))
             => non-null-wb-tree-node?)
  (desc "
* It is an error if `left` or `right` are not balanced.
* It is an error if any element of `left` is greater than or equal to
  any element in `right`.
* It is an error if `data` is less than or equal to any element in
  `left`.
* It is an error if `data` is greater than or equal to any element in
  `right`.

Returns a balanced tree containing all elements of `left` and `right`
with `data`."))
 ((name . "join2")
  (signature lambda ((wb-tree-node? left) (wb-tree-node? right))
             => wb-tree-node?)
  (desc "
* It is an error if any element in `left` is greater than or equal to any
  element in `right`.

Returns a new tree with the elements of `left` and `right`."))
 ((name . "split")
  (signature lambda ((comparator? cmp) (wb-tree-node? tree) key (procedure? default))
             => (values wb-tree-node? * wb-tree-node?))
  "
* It is an error if any element of `tree` is not comparable by `cmp`.
* It is an error if `key` is not comparable by `cmp`.
* It is an error if `cmp` does not have an order.
* It is an error if `default` is not a thunk.

Returns two trees, one of all values to the left of `key`, and one with
all values to the right of `key`.

If a value that compares equal to `key` is found, that value is returned.
Otherwise the result of calling `default` with no arguments is returned.")
 ((name . "search")
  (signature case-lambda ((((wb-tree-node? tree) (comparator? cmp) key) *)
                          (((wb-tree-node? tree) (comparator? cmp) key (procedure? default)) *)))
  (desc "
* It is an error if `cmp` does not order `key` and all elements in `tree`.
* It is an error if `default` is not a thunk.

Searches `tree` for `key` using `cmp`. If a node contains data that compares equal
to `key`, return that data. Otherwise, tail call `default.` If `default` is not
supplied, the function returns `#f`.")))