private function rotateRight()
    {
        $left = $this->left;

        if ($left->information & 1) {
            $this->left = $left->right;
            $left->right = $this;
        } else {
            $this->information &= ~ 2;
            $left->information |= 1;
        }

        $this->information += 4;

        if ($left->information < 0) {
            $this->information -= $left->information & ~3;
        }

        $left->information += 4;

        if ($this->information >= 4) {
            $left->information += $this->information & ~3;
        }

        return $left;
    }