code: def clear_env_vars():
      os.environ.pop("MLFLOW_EXPERIMENT_NAME", None)
      os.environ.pop("MLFLOW_EXPERIMENT_ID", None)
  
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 1 for calling a global function with example usage: clear_env_vars() without return types