@abc.abstractmethod<EOL><INDENT>def get_rule(self):<DEDENT>
return<EOL>
Gets the explicit rule.

        :return: the rule
        :rtype: ``osid.rules.Rule``
        :raise: ``IllegalState`` -- ``has_rule()`` is ``false``
        :raise: ``OperationFailed`` -- unable to complete request

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