public function diff()
    {
        $result = [];

        foreach ($this->keys() as $key) {
            if ($diff = $this->equal($key)) {
                $result[] = $diff; continue;
            }

            if ($diff = $this->delete($key)) {
                $result[] = $diff;
            }

            if ($diff = $this->insert($key)) {
                $result[] = $diff;
            }
        }

        return $result;
    }