def _load_dataset(self) -> None:
        """
        The standardized dataset download and load procedure.

        For more details on the coded procedure see the class documentation.

        This method shouldn't be overridden.

        This method will raise and error if the dataset couldn't be loaded
        or downloaded.

        :return: None
        """
        metadata_loaded = False
        metadata_load_error = None
        try:
            metadata_loaded = self._load_metadata()
        except Exception as e:
            metadata_load_error = e

        if metadata_loaded:
            if self.verbose:
                print("Files already downloaded and verified")
            return

        if not self.download:
            msg = (
                "Error loading dataset metadata (dataset download was "
                'not attempted as "download" is set to False)'
            )
            if metadata_load_error is None:
                raise RuntimeError(msg)
            else:
                print(msg)
                raise metadata_load_error

        try:
            self._download_dataset()
        except Exception as e:
            err_msg = self._download_error_message()
            print(err_msg, flush=True)
            raise e

        if not self._load_metadata():
            err_msg = self._download_error_message()
            print(err_msg)
            raise RuntimeError(
                "Error loading dataset metadata (... but the download "
                "procedure completed successfully)"
            )

        The standardized dataset download and load procedure.

        For more details on the coded procedure see the class documentation.

        This method shouldn't be overridden.

        This method will raise and error if the dataset couldn't be loaded
        or downloaded.

        :return: None
        
avalanche/benchmarks/datasets/downloadable_dataset.py