langchain/document_loaders/blackboard.py/BlackboardLoader/_download_attachments
class BlackboardLoader:    def _download_attachments(self, attachments: List[str]) -> None:
        """Download all attachments.

        Args:
            attachments: List of attachments.
        """
        # Make sure the folder exists
        Path(self.folder_path).mkdir(parents=True, exist_ok=True)
        # Download all attachments
        for attachment in attachments:
            self.download(attachment)