@abc.abstractmethod<EOL><INDENT>def get_end_reason_id(self):<DEDENT>
return<EOL>
Gets a state ``Id`` indicating why this relationship has ended.

        :return: a state ``Id``
        :rtype: ``osid.id.Id``
        :raise: ``IllegalState`` -- ``has_end_reason()`` is ``false``

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