code: def __str__(self):
      return self.trial_name
  
imports: import os
  import shutil
  import tempfile
  import unittest
  from collections import namedtuple
  from unittest.mock import patch
  from mlflow.tracking import MlflowClient
  from ray._private.dict import flatten_dict
  from ray.train._internal.session import init_session, shutdown_session
  from ray.train._internal.storage import StorageContext
  from ray.air.integrations.mlflow import MLflowLoggerCallback, setup_mlflow, _NoopModule
  from ray.air._internal.mlflow import _MLflowLoggerUtil
label_desc: Use image node_id 2 for calling the MockTrial obj's underlying member method code with example usage: obj.__str__() and returns: self