langchain/document_loaders/blob_loaders/schema.py/Blob/check_blob_is_valid
class Blob:    def check_blob_is_valid(cls, values: Mapping[str, Any]) -> Mapping[str, Any]:
        """Verify that either data or path is provided."""
        if "data" not in values and "path" not in values:
            raise ValueError("Either data or path must be provided")
        return values