src/transformers/pipelines/text2text_generation.py/Text2TextGenerationPipeline/_parse_and_tokenize
class Text2TextGenerationPipeline:    def _parse_and_tokenize(self, *args, truncation):
        prefix = self.model.config.prefix if self.model.config.prefix is not None else ""
        if isinstance(args[0], list):
            if self.tokenizer.pad_token_id is None:
                raise ValueError("Please make sure that the tokenizer has a pad_token_id when using a batch input")
            args = ([prefix + arg for arg in args[0]],)
            padding = True

        elif isinstance(args[0], str):
            args = (prefix + args[0],)
            padding = False
        else:
            raise ValueError(
                f" `args[0]`: {args[0]} have the wrong format. The should be either of type `str` or type `list`"
            )
        inputs = self.tokenizer(*args, padding=padding, truncation=truncation, return_tensors=self.framework)
        # This is produced by tokenizers but is an invalid generate kwargs
        if "token_type_ids" in inputs:
            del inputs["token_type_ids"]
        return inputs