def get_book_search_session(self):
raise Unimplemented()<EOL>
Gets the ``OsidSession`` associated with the book search service.

        return: (osid.commenting.BookSearchSession) - a
                ``BookSearchSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_book_search()`` is ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_book_search()`` is ``true``.*