@abc.abstractmethod<EOL><INDENT>def search_among_activities(self, activity_ids):<DEDENT>
pass<EOL>
Execute this search among the given list of activities.

        :param activity_ids: list of activities
        :type activity_ids: ``osid.id.IdList``
        :raise: ``NullArgument`` -- ``activity_ids`` is ``null``

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