Returns the members of a list.

        List id or (slug and (owner_screen_name or owner_id)) are required

def list_members(self, list_id=None, slug=None, owner_screen_name=None, owner_id=None):
        """
        Returns the members of a list.

        List id or (slug and (owner_screen_name or owner_id)) are required
        """
        assert list_id or (slug and (owner_screen_name or owner_id))
        url = 'https://api.twitter.com/1.1/lists/members.json'
        params = {'cursor': -1}
        if list_id:
            params['list_id'] = list_id
        else:
            params['slug'] = slug
            if owner_screen_name:
                params['owner_screen_name'] = owner_screen_name
            else:
                params['owner_id'] = owner_id

        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.error("no matching list")
                raise e

            users = resp.json()
            for user in users['users']:
                yield user
            params['cursor'] = users['next_cursor']