src/transformers/pipelines/zero_shot_classification.py/ZeroShotClassificationArgumentHandler/__call__
class ZeroShotClassificationArgumentHandler:    def __call__(self, sequences, labels, hypothesis_template):
        if len(labels) == 0 or len(sequences) == 0:
            raise ValueError("You must include at least one label and at least one sequence.")
        if hypothesis_template.format(labels[0]) == hypothesis_template:
            raise ValueError(
                (
                    'The provided hypothesis_template "{}" was not able to be formatted with the target labels. '
                    "Make sure the passed template includes formatting syntax such as {{}} where the label should go."
                ).format(hypothesis_template)
            )

        if isinstance(sequences, str):
            sequences = [sequences]

        sequence_pairs = []
        for sequence in sequences:
            sequence_pairs.extend([[sequence, hypothesis_template.format(label)] for label in labels])

        return sequence_pairs, sequences