def METHOD_NAME(forecaster, transformers, cv, y):
    """Evaluate all the transformers on y and return the name of best."""
    scoring = check_scoring(None)
    scoring_name = f"test_{scoring.name}"
    score = None
    for name, transformer in transformers:
        test_transformer = clone(transformer)
        y_hat = test_transformer.fit_transform(y)
        results = evaluate(clone(forecaster), cv, y_hat)
        results = results.mean(numeric_only=True)
        new_score = float(results[scoring_name])
        if not score or new_score < score:
            score = new_score
            best_name = name
    return best_name