find xml
        :param url: contents url
        :param features: markup provider
        :param headers: http header
        :return: BeautifulSoup object

def find_xml(cls, url, features):
        """
        find xml
        :param url: contents url
        :param features: markup provider
        :param headers: http header
        :return: BeautifulSoup object
        """
        req = cls._get_content(url)
        if req.status_code in range(200, 300):
            return BeautifulSoup(req.text, features)
        else:
            raise MlbAmHttpNotFound('HTTP Error url: {url} status: {status}'.format(url=url, status=req.status_code))