Count the number of accounts for a given domain, sorted by cos

        :returns: a list of pairs <ClassOfService object>,count

def count_account(self, domain):
        """ Count the number of accounts for a given domain, sorted by cos

        :returns: a list of pairs <ClassOfService object>,count
        """
        selector = domain.to_selector()
        cos_list = self.request_list('CountAccount', {'domain': selector})
        ret = []

        for i in cos_list:
            count = int(i['_content'])
            ret.append((zobjects.ClassOfService.from_dict(i),  count))

        return list(ret)