examples/pytorch/semantic-segmentation/run_semantic_segmentation.py/DataTrainingArguments/__post_init__
class DataTrainingArguments:    def __post_init__(self):
        if self.dataset_name is None and (self.train_dir is None and self.validation_dir is None):
            raise ValueError(
                "You must specify either a dataset name from the hub or a train and/or validation directory."
            )