@abc.abstractmethod<EOL><INDENT>def set_level(self, grade):<DEDENT>
pass<EOL>
Sets the level expressed as a ``Grade``.

        :param grade: the level
        :type grade: ``osid.grading.Grade``
        :raise: ``InvalidArgument`` -- ``grade`` is invalid
        :raise: ``NoAccess`` -- ``Metadata.isReadOnly()`` is ``true``
        :raise: ``NullArgument`` -- ``grade`` is ``null``

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