def save_vocabulary(self, save_directory: str, filename_prefix: Optional[str] = None) -> Tuple[str]:
        """
        Saves the tokenizer's vocabulary dictionary to the provided save_directory.

        Args:
            save_directory (`str`):
                A path to the directory where to saved. It will be created if it doesn't exist.
            filename_prefix (`Optional[str]`, *optional*):
                A prefix to add to the names of the files saved by the tokenizer.
        """
        if not os.path.isdir(save_directory):
            logger.error(f"Vocabulary path ({save_directory}) should be a directory")
            return

        # Save the encoder.
        out_vocab_file = os.path.join(
            save_directory, (filename_prefix + "-" if filename_prefix else "") + VOCAB_FILES_NAMES["vocab"]
        )
        with open(out_vocab_file, "w") as file:
            file.write(json.dumps(self.encoder))

        return (out_vocab_file,)

        Saves the tokenizer's vocabulary dictionary to the provided save_directory.

        Args:
            save_directory (`str`):
                A path to the directory where to saved. It will be created if it doesn't exist.
            filename_prefix (`Optional[str]`, *optional*):
                A prefix to add to the names of the files saved by the tokenizer.
        
dpkd/transformers/src/transformers/models/pop2piano/tokenization_pop2piano.py