'Check if the country is either in whitelist or blacklist of countries for the course_id
Args:
course_id (str): course_id to look for
country (str): A 2 characters code of country
Returns:
Boolean
True if country found in allowed country
otherwise check given country exists in list'

@classmethod
def check_country_access(cls, course_id, country):

    if (country not in cls.ALL_COUNTRIES):
        return True
    cache_key = cls.CACHE_KEY.format(course_key=course_id)
    allowed_countries = cache.get(cache_key)
    if (allowed_countries is None):
        allowed_countries = cls._get_country_access_list(course_id)
        cache.set(cache_key, allowed_countries)
    return ((country == '') or (country in allowed_countries))
