code: def report_cross_validation_scores(
      trial: Trial, scores: list[float]
  ) -> None:
      """A function to report cross-validation scores of a trial.
  
      This function should be called within the objective function to report the cross-validation
      scores. The reported scores are used to evaluate the statistical error for termination
      judgement.
  
      Args:
          trial:
              A :class:`~optuna.trial.Trial` object to report the cross-validation scores.
          scores:
              The cross-validation scores of the trial.
  
      """
      if len(scores) <= 1:
          raise ValueError(
              "The length of `scores` is expected to be greater than one."
          )
      trial.storage.set_trial_system_attr(
          trial._trial_id, _CROSS_VALIDATION_SCORES_KEY, scores
      )
  
file_path: optuna/optuna/terminator/erroreval.py
imports: from __future__ import annotations
  import abc
  from typing import cast
  import numpy
  from optuna._experimental import experimental_class
  from optuna.study import StudyDirection
  from optuna.trial import FrozenTrial
  from optuna.trial import Trial
  from optuna.trial._state import TrialState
label_desc: Use image node_id 1 for calling a global function with example usage: report_cross_validation_scores(trial, scores) without return types