@abc.abstractmethod<EOL><INDENT>def get_resource_relationship(self, resource_relationship_id):<DEDENT>
return<EOL>
Gets the ``ResourceRelationship`` specified by its ``Id``.

        :param resource_relationship_id: ``Id`` of the ``Relationship``
        :type resource_relationship_id: ``osid.id.Id``
        :return: the relationship
        :rtype: ``osid.resource.ResourceRelationship``
        :raise: ``NotFound`` -- ``resource_relationship_id`` not found
        :raise: ``NullArgument`` -- ``resource_relationship_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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