protected function before($key = null)
    {
        if (! $this->before) {
            $this->before = $this->parseData($this->activity->before);
        }

        if (! $key) {
            return array_keys($this->before);
        }

        if (! isset($this->before[$key]) || $this->before[$key] === '') {
            return null;
        }

        return $this->before[$key];
    }