langchain/document_loaders/blackboard.py/BlackboardLoader/check_bs4
class BlackboardLoader:    def check_bs4(self) -> None:
        """Check if BeautifulSoup4 is installed.

        Raises:
            ImportError: If BeautifulSoup4 is not installed.
        """
        try:
            import bs4  # noqa: F401
        except ImportError:
            raise ImportError(
                "BeautifulSoup4 is required for BlackboardLoader. "
                "Please install it with `pip install beautifulsoup4`."
            )