src/transformers/data/data_collator.py/DefaultDataCollator/__call__
class DefaultDataCollator:    def __call__(self, features: List[Dict[str, Any]], return_tensors=None) -> Dict[str, Any]:
        if return_tensors is None:
            return_tensors = self.return_tensors
        return default_data_collator(features, return_tensors)