code: def _metric_names_for_training_job(self):
          
          training_description = self._sage_client.describe_training_job(TrainingJobName=self._training_job_name)
  
          metric_definitions = training_description['AlgorithmSpecification']['MetricDefinitions']
          metric_names = [md['Name'] for md in metric_definitions]
  
          return metric_names
docs: Helper method to discover the metrics defined for a training job.