/**
* Delete node by key
* @param KeyInterface $key
*/
public function delete(KeyInterface $key)
{
if (!$this->root->getLeft()->isRed() && !$this->root->getRight()->isRed()) {
$this->root->setColor(Node::RED);
}
$this->_delete($this->root, $key);
if (!$this->root->isEmpty()) {
$this->root->setColor(Node::BLACK);
}
}