function addSideService(address _service, uint _block) public returns (uint _code) {
        if (sideServices[_service]) {
            return SERVICE_CONTROLLER_SERVICE_EXIST;
        }
        _code = _multisig(keccak256(_service), _block);
        if (OK != _code) {
            return _code;
        }

        sideServices[_service] = true;
        return OK;
    }