How to use the workflows.pipe-common.scripts.autoscale_sge.Logger.warn function in workflows

def execute(self, command):
        process = subprocess.Popen(command, shell=True, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
        out, err = process.communicate()
        exit_code = process.wait()
        if exit_code != 0:
            Logger.warn('Command \'%s\' execution has failed due to %s.' % (command, err))
            raise ExecutionError('Command \'%s\' execution has failed due to %s.' % (command, err))
        return out

def scale_down(self, child_host):
        """
        Kills pipeline, removes it from the GE cluster configuration.
        Also removes host from master /etc/hosts and self.default_hostfile.

        :param child_host: Host name of the pipeline to be killed.
        :return: True if the pipeline killing went well, False otherwise.
        """
        Logger.info('Disable additional worker with host=%s.' % child_host)
        self.grid_engine.disable_host(child_host)
        jobs = self.grid_engine.get_jobs()
        disabled_host_jobs = [job for job in jobs if job.host == child_host]
        if disabled_host_jobs:
            Logger.warn('Disabled additional worker with host=%s has %s associated jobs. Scaling down is interrupted.'
                        % (child_host, len(disabled_host_jobs)))
            Logger.info('Enable additional worker with host=%s again.' % child_host)
            self.grid_engine.enable_host(child_host)
            return False
        self._decrease_parallel_environment_slots(self.instance_cores)
        self._remove_host_from_grid_engine_configuration(child_host)
        self._stop_pipeline(child_host)
        self._remove_host_from_hosts(child_host)
        self._remove_host_from_default_hostfile(child_host)
        Logger.info('Additional worker with host=%s has been stopped.' % child_host, crucial=True)
        return True

def is_valid(self, host):
        """
        Validates host in GE checking corresponding execution host availability.

        :param host: Host to be checked.
        :return: True if execution host exists.
        """
        try:
            self.cmd_executor.execute_to_lines(GridEngine._SHOW_EXECUTION_HOST % host)
            return True
        except RuntimeError:
            Logger.warn('Execution host %s in GE wasn\'t found.' % host)
            return False

def _try_stop_worker(self, run_id):
        try:
            Logger.info('Stop pipeline with run_id=%s' % run_id)
            self.executor.execute(GridEngineWorkerValidator._STOP_PIPELINE % run_id)
        except:
            Logger.warn('Invalid additional worker disabling has failed.')

def start(self):
        while True:
            try:
                time.sleep(self.timeout)
                self.worker_validator.validate_hosts()
                self.autoscaler.scale()
            except KeyboardInterrupt:
                Logger.warn('Manual stop the autoscaler daemon.')
                break
            except Exception as e:
                Logger.fail('Scaling step has failed due to %s.' % e)

def validate_hosts(self):
        """
        Checks additional hosts if they are valid execution hosts in GE and kills invalid ones.
        """
        hosts = self.host_storage.load_hosts()
        Logger.info('Validate %s additional workers.' % len(hosts))
        invalid_hosts = [host for host in hosts if not self.grid_engine.is_valid(host)]
        for host in invalid_hosts:
            Logger.warn('Invalid additional host %s was found. It will be downscaled.' % host)
            run_id = self.scale_down_handler._get_run_id_from_host(host)
            self._try_stop_worker(run_id)
            self._try_disable_worker(host, run_id)
            self._try_kill_invalid_host_jobs(host)
            self.grid_engine.delete_host(host, skip_on_failure=True)
            self._remove_worker_from_hosts(host)
            self.host_storage.remove_host(host)
        Logger.info('Additional hosts validation has finished.')

def _try_disable_worker(self, host, run_id):
        try:
            Logger.info('Disable worker in GE with run_id=%s' % run_id)
            self.grid_engine.disable_host(host)
        except:
            Logger.warn('Invalid additional worker disabling has failed.')

def _perform_command(self, action, msg, error_msg, skip_on_failure):
        Logger.info(msg)
        try:
            action()
        except RuntimeError as e:
            Logger.warn(error_msg)
            if not skip_on_failure:
                raise RuntimeError(error_msg, e)