How to use the nni.protocol.send function in nni

if data['type'] == MetricType.REQUEST_PARAMETER:
            assert multi_phase_enabled()
            assert data['trial_job_id'] is not None
            assert data['parameter_index'] is not None
            assert data['trial_job_id'] in self.job_id_para_id_map
            self._handle_trial_end(self.job_id_para_id_map[data['trial_job_id']])
            ret = self._get_one_trial_job()
            if ret is None:
                self.unsatisfied_jobs.append({'trial_job_id': data['trial_job_id'], 'parameter_index': data['parameter_index']})
            else:
                ret['trial_job_id'] = data['trial_job_id']
                ret['parameter_index'] = data['parameter_index']
                # update parameter_id in self.job_id_para_id_map
                self.job_id_para_id_map[data['trial_job_id']] = ret['parameter_id']
                send(CommandType.SendTrialJobParameter, json_tricks.dumps(ret))
        else:
            assert 'value' in data
            value = extract_scalar_reward(data['value'])
            if self.optimize_mode is OptimizeMode.Maximize:
                reward = -value
            else:
                reward = value
            assert 'parameter_id' in data
            s, i, _ = data['parameter_id'].split('_')
            logger.debug('bracket id = %s, metrics value = %s, type = %s', s, value, data['type'])
            s = int(s)

            # add  to self.job_id_para_id_map here,
            # because when the first parameter_id is created, trial_job_id is not known yet.
            if data['trial_job_id'] in self.job_id_para_id_map:
                assert self.job_id_para_id_map[data['trial_job_id']] == data['parameter_id']

def _send_new_trial(self):
        while self.unsatisfied_jobs:
            ret = self._get_one_trial_job()
            if ret is None:
                break
            one_unsatisfied = self.unsatisfied_jobs.pop(0)
            ret['trial_job_id'] = one_unsatisfied['trial_job_id']
            ret['parameter_index'] = one_unsatisfied['parameter_index']
            # update parameter_id in self.job_id_para_id_map
            self.job_id_para_id_map[ret['trial_job_id']] = ret['parameter_id']
            send(CommandType.SendTrialJobParameter, json_tricks.dumps(ret))
        for _ in range(self.credit):
            self._request_one_trial_job()

def handle_request_trial_jobs(self, data):
        # data: number or trial jobs
        ids = [_create_parameter_id() for _ in range(data)]
        params_list = self.tuner.generate_multiple_parameters(ids)
        assert len(ids) == len(params_list)
        for i, _ in enumerate(ids):
            send(CommandType.NewTrialJob, _pack_parameter(ids[i], params_list[i]))
        return True

a. If there is a parameter need to run, will return "NewTrialJob" with a dict:
        {
            'parameter_id': id of new hyperparameter
            'parameter_source': 'algorithm'
            'parameters': value of new hyperparameter
        }
        b. If BOHB don't have parameter waiting, will return "NoMoreTrialJobs" with
        {
            'parameter_id': '-1_0_0',
            'parameter_source': 'algorithm',
            'parameters': ''
        }
        """
        ret = self._get_one_trial_job()
        if ret is not None:
            send(CommandType.NewTrialJob, json_tricks.dumps(ret))
            self.credit -= 1

return True

        try:
            result = self.assessor.assess_trial(trial_job_id, ordered_history)
        except Exception as e:
            _logger.exception('Assessor error')

        if isinstance(result, bool):
            result = AssessResult.Good if result else AssessResult.Bad
        elif not isinstance(result, AssessResult):
            msg = 'Result of Assessor.assess_trial must be an object of AssessResult, not %s'
            raise RuntimeError(msg % type(result))

        if result is AssessResult.Bad:
            _logger.debug('BAD, kill %s', trial_job_id)
            send(CommandType.KillTrialJob, json_tricks.dumps(trial_job_id))
        else:
            _logger.debug('GOOD')

def handle_request_trial_jobs(self, data):
        """
        Parameters
        ----------
        data: int
            number of trial jobs
        """
        for _ in range(data):
            ret = self._get_one_trial_job()
            send(CommandType.NewTrialJob, json_tricks.dumps(ret))

'parameters': value of new hyperparameter
        }
        b. If BOHB don't have parameter waiting, will return "NoMoreTrialJobs" with
        {
            'parameter_id': '-1_0_0',
            'parameter_source': 'algorithm',
            'parameters': ''
        }
        """
        if not self.generated_hyper_configs:
            ret = {
                'parameter_id': '-1_0_0',
                'parameter_source': 'algorithm',
                'parameters': ''
            }
            send(CommandType.NoMoreTrialJobs, json_tricks.dumps(ret))
            return None
        assert self.generated_hyper_configs
        params = self.generated_hyper_configs.pop(0)
        ret = {
            'parameter_id': params[0],
            'parameter_source': 'algorithm',
            'parameters': params[1]
        }
        self.parameters[params[0]] = params[1]
        return ret

def handle_initialize(self, data):
        """callback for initializing the advisor
        Parameters
        ----------
        data: dict
            search space
        """
        self.handle_update_search_space(data)
        send(CommandType.Initialized, '')