# LLRB for Chez Scheme
A basic implementation of a left-leaning red-black tree for Chez Scheme.

## Functions
```
(make-tree cmp)
```
Create a new tree using the comparison function `(cmp a b)`, which returns a negative number if `a < b`, zero if `a = b`, and a positive number if `a > b` (or vice-versa).

```
(tree-insert! t key value)
```
Insert `value` at `key` in tree `t`. This will replace an existing node or create a new one if the key doesn't exist. Returns `t`.

```
(tree-delete! t key)
```
Delete the value at `key` in tree `t`. Returns `#t` if `key` was present and `#f` otherwise.

```
(tree-search t key)
```
Search the tree `t` for `key` and return its value; if not found, raises `not-found`.

```
(tree-get t key not-found)
```
Search the tree `t` for `key` and return its value; if not found, returns `not-found`.

```
(tree-has? t key)
```
Check if the tree `t` has `key`.