@abc.abstractmethod<EOL><INDENT>def get_assets(self):<DEDENT>
return<EOL>
Gets any assets associated with this activity.

        :return: list of assets
        :rtype: ``osid.repository.AssetList``
        :raise: ``IllegalState`` -- ``is_asset_based_activity()`` is ``false``
        :raise: ``OperationFailed`` -- unable to complete request

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