code: def _validate_log_to_file(log_to_file):
      """Validate ``train.RunConfig``'s ``log_to_file`` parameter. Return
      validated relative stdout and stderr filenames."""
      if not log_to_file:
          stdout_file = stderr_file = None
      elif isinstance(log_to_file, bool) and log_to_file:
          stdout_file = "stdout"
          stderr_file = "stderr"
      elif isinstance(log_to_file, str):
          stdout_file = stderr_file = log_to_file
      elif isinstance(log_to_file, Sequence):
          if len(log_to_file) != 2:
              raise ValueError(
                  "If you pass a Sequence to `log_to_file` it has to have "
                  "a length of 2 (for stdout and stderr, respectively). The "
                  "Sequence you passed has length {}.".format(
                      len(log_to_file)
                  )
              )
          stdout_file, stderr_file = log_to_file
      else:
          raise ValueError(
              "You can pass a boolean, a string, or a Sequence of length 2 to "
              "`log_to_file`, but you passed something else ({}).".format(
                  type(log_to_file)
              )
          )
      return stdout_file, stderr_file
  
imports: import copy
  import datetime
  from functools import partial
  import logging
  from pathlib import Path
  from pickle import PicklingError
  import pprint
  import traceback
  from typing import Any, Dict, Optional, Sequence, Union, Callable, Type, List, Mapping, TYPE_CHECKING
  import ray
  from ray.exceptions import RpcError
  from ray.train import CheckpointConfig, SyncConfig
  from ray.train._internal.storage import StorageContext
  from ray.tune.error import TuneError
  from ray.tune.registry import register_trainable, is_function_trainable
  from ray.tune.stopper import CombinedStopper, FunctionStopper, Stopper, TimeoutStopper
  from ray.util.annotations import DeveloperAPI, Deprecated
label_desc: Use image node_id 1 for calling a global function with example usage: _validate_log_to_file(log_to_file) and returns: stdout_file,  stderr_file