    protected function getStringBetween($content, $start, $ending)
    {
        $startPosition = \mb_strpos($content, $start);
        if ($startPosition === false) {
            return null;
        }

        $endPosition = \mb_strpos($content, $ending, $startPosition + \mb_strlen($start));
        if ($endPosition === false) {
            return null;
        }

        return \mb_substr($content, $startPosition, $endPosition);
    }