src/transformers/pipelines/base.py/Pipeline/preprocess
class Pipeline:    def preprocess(self, input_: Any, **preprocess_parameters: Dict) -> Dict[str, GenericTensor]:
        """
        Preprocess will take the `input_` of a specific pipeline and return a dictionnary of everything necessary for
        `_forward` to run properly. It should contain at least one tensor, but might have arbitrary other items.
        """
        raise NotImplementedError("preprocess not implemented")