*/ public function children() : Traversable; /** * The balance factor of the node. Negative numbers indicate a lean to the left, positive * to the right, and 0 is perfectly balanced. * * @return int */ public function balance() : int; /** * Set the left child node. * * @param BinaryNode|null $node */ public function attachLeft(?BinaryNode $node = null) : void; /** * Set the right child node. * * @param BinaryNode|null $node */ public function attachRight(?BinaryNode $node = null) : void; }