@abc.abstractmethod<EOL><INDENT>def add_root_book(self, book_id):<DEDENT>
pass<EOL>
Adds a root book.

        :param book_id: the ``Id`` of a book
        :type book_id: ``osid.id.Id``
        :raise: ``AlreadyExists`` -- ``book_id`` is already in hierarchy
        :raise: ``NotFound`` -- ``book_id`` is not found
        :raise: ``NullArgument`` -- ``book_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

        *compliance: mandatory -- This method must be implemented.*