reference_key=reference_key,
            tags=[eval_type_tag],
        )
    elif isinstance(evaluator_, PairwiseStringEvaluator):
        raise NotImplementedError(
            f"Run evaluator for {eval_type_tag} is not implemented."
            " PairwiseStringEvaluators compare the outputs of two different models"
            " rather than the output of a single model."
            " Did you mean to use a StringEvaluator instead?"
            "\nSee: https://python.langchain.com/docs/guides/evaluation/string/"
        )
    else:
        raise NotImplementedError(
            f"Run evaluator for {eval_type_tag} is not implemented"
        )
    return run_evaluator
def _get_keys(
    config: smith_eval.RunEvalConfig,
    run_inputs: Optional[List[str]],
    run_outputs: Optional[List[str]],
    example_outputs: Optional[List[str]],
) -> Tuple[Optional[str], Optional[str], Optional[str]]:
    input_key = _determine_input_key(config, run_inputs)
    prediction_key = _determine_prediction_key(config, run_outputs)
    reference_key = _determine_reference_key(config, example_outputs)
    return input_key, prediction_key, reference_key
def _load_run_evaluators(
    config: smith_eval.RunEvalConfig,
    run_type: str,
    data_type: DataType,
    example_outputs: Optional[List[str]],
    run_inputs: Optional[List[str]],
    run_outputs: Optional[List[str]],
) -> List[RunEvaluator]:
    """
    Load run evaluators from a configuration.
    Args:
        config: Configuration for the run evaluators.
    Returns:
        A list of run evaluators.
    """
    run_evaluators = []