'Check that all rules belong to the same security group and tenant'

def _validate_single_tenant_and_group(self, security_group_rules):

    sg_groups = set()
    tenants = set()
    for rule_dict in security_group_rules['security_group_rules']:
        rule = rule_dict['security_group_rule']
        sg_groups.add(rule['security_group_id'])
        if (len(sg_groups) > 1):
            raise ext_sg.SecurityGroupNotSingleGroupRules()
        tenants.add(rule['tenant_id'])
        if (len(tenants) > 1):
            raise ext_sg.SecurityGroupRulesNotSingleTenant()
    return sg_groups.pop()
