chalup

sealed class RedBlackTree<E : Comparable<E>> {
    enum class Color { R, B }

    companion object {
        fun <T : Comparable<T>> emptyTree(): RedBlackTree<T> = Empty as RedBlackTree<T>
    }

    object Empty : RedBlackTree<Nothing>()
    data class Tree<E : Comparable<E>>(
        val color: Color,