code: def assert_unauthenticated():
      with pytest.raises(
          MlflowException, match=r"You are not authenticated."
      ) as exception_context:
          yield
      assert exception_context.value.error_code == ErrorCode.Name(
          UNAUTHENTICATED
      )
  
imports: import os
  from contextlib import contextmanager
  import pytest
  import mlflow
  from mlflow import MlflowException
  from mlflow.environment_variables import MLFLOW_TRACKING_PASSWORD, MLFLOW_TRACKING_USERNAME
  from mlflow.protos.databricks_pb2 import PERMISSION_DENIED, RESOURCE_DOES_NOT_EXIST, UNAUTHENTICATED, ErrorCode
  from mlflow.server.auth import auth_config
  from mlflow.server.auth.client import AuthServiceClient
  from mlflow.utils.os import is_windows
  from tests.helper_functions import random_str
  from tests.server.auth.auth_test_utils import ADMIN_PASSWORD, ADMIN_USERNAME, NEW_PERMISSION, PERMISSION, User, create_user
  from tests.tracking.integration_test_utils import _init_server
label_desc: Use image node_id 3 for calling a global function with example usage: assert_unauthenticated() without return types