@abc.abstractmethod<EOL><INDENT>def order_by_state(self, process_id, style):<DEDENT>
pass<EOL>
Orders by the state in a given ``Process``.

        :param process_id: a process ``Id``
        :type process_id: ``osid.id.Id``
        :param style: search order style
        :type style: ``osid.SearchOrderStyle``
        :raise: ``NullArgument`` -- ``process_id`` or ``style`` is ``null``

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