def METHOD_NAME(self, unsafe_file_name: str) -> BinaryIO:
    try:
        safe_file_path = self._get_safe_file_path(unsafe_file_name)
        return open(safe_file_path, "rb")
    except FileNotFoundError as err:
        # Wrap Python's FileNotFound error, which is-an OSError,
        # in repositories.FileNotFoundError
        raise repositories.FileNotFoundError(
            f'The requested file "{unsafe_file_name}" does not exist: {err}'
        )
    except Exception as err:
        raise RetrievalError(
            f'Error retrieving file "{unsafe_file_name}" from the repository: {err}'
        )