@abc.abstractmethod<EOL><INDENT>def get_hierarchy_search_order(self):<DEDENT>
return<EOL>
Gets a hierarchy search order.

        The ``HierarchySearchOrder`` is supplied to a
        ``HierarchySearch`` to specify the ordering of results.

        :return: the hierarchy search order
        :rtype: ``osid.hierarchy.HierarchySearchOrder``


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