@classmethod
def _validate_create_tuner_inputs(cls, estimator_dict,
    objective_metric_name_dict, hyperparameter_ranges_dict,
    metric_definitions_dict=None):
    """Validate inputs for ``HyperparameterTuner.create()``"""
    cls._validate_estimator_dict(estimator_dict)
    estimator_names = sorted(estimator_dict.keys())
    cls._validate_dict_argument(name='objective_metric_name_dict', value=
        objective_metric_name_dict, allowed_keys=estimator_names,
        require_same_keys=True)
    cls._validate_dict_argument(name='hyperparameter_ranges_dict', value=
        hyperparameter_ranges_dict, allowed_keys=estimator_names,
        require_same_keys=True)
    cls._validate_dict_argument(name='metric_definitions_dict', value=
        metric_definitions_dict, allowed_keys=estimator_names)
