src/transformers/models/rag/tokenization_rag.py/RagTokenizer/save_pretrained
class RagTokenizer:    def save_pretrained(self, save_directory):
        if os.path.isfile(save_directory):
            raise ValueError(f"Provided path ({save_directory}) should be a directory, not a file")
        os.makedirs(save_directory, exist_ok=True)
        question_encoder_path = os.path.join(save_directory, "question_encoder_tokenizer")
        generator_path = os.path.join(save_directory, "generator_tokenizer")
        self.question_encoder.save_pretrained(question_encoder_path)
        self.generator.save_pretrained(generator_path)