@abc.abstractmethod<EOL><INDENT>def get_id_aliases_by_authority(self, id_, authority):<DEDENT>
return<EOL>
Gets a list of ``Id`` aliases in a authority for an ``Id``.

        :param id: an ``Id``
        :type id: ``osid.id.Id``
        :param authority: an authority
        :type authority: ``string``
        :return: a list of alias ``Ids``
        :rtype: ``osid.id.IdList``
        :raise: ``NullArgument`` -- ``id`` or ``authority`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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