public interface TreeFactory
<K,V> Tree<K,V>
black(K key, V value, Tree<K,V> left, Tree<K,V> right)
red(K key, V value, Tree<K,V> left, Tree<K,V> right)
<K,V> Tree<K,V> red(K key, V value, Tree<K,V> left, Tree<K,V> right)
<K,V> Tree<K,V> black(K key, V value, Tree<K,V> left, Tree<K,V> right)