langchain/document_loaders/email.py/OutlookMessageLoader/__init__
class OutlookMessageLoader:    def __init__(self, file_path: str):
        """Initialize with file path."""

        self.file_path = file_path

        if not os.path.isfile(self.file_path):
            raise ValueError("File path %s is not a valid file" % self.file_path)

        try:
            import extract_msg  # noqa:F401
        except ImportError:
            raise ImportError(
                "extract_msg is not installed. Please install it with "
                "`pip install extract_msg`"
            )