Returns Twitter user id lists for the specified user's followers.
        A user can be a specific using their screen_name or user_id

def follower_ids(self, user):
        """
        Returns Twitter user id lists for the specified user's followers.
        A user can be a specific using their screen_name or user_id
        """
        user = str(user)
        user = user.lstrip('@')
        url = 'https://api.twitter.com/1.1/followers/ids.json'

        if re.match(r'^\d+$', user):
            params = {'user_id': user, 'cursor': -1}
        else:
            params = {'screen_name': user, 'cursor': -1}

        while params['cursor'] != 0:
            try:
                resp = self.get(url, params=params, allow_404=True)
            except requests.exceptions.HTTPError as e:
                if e.response.status_code == 404:
                    log.info("no users matching %s", screen_name)
                raise e
            user_ids = resp.json()
            for user_id in user_ids['ids']:
                yield str_type(user_id)
            params['cursor'] = user_ids['next_cursor']