@abc.abstractmethod<EOL><INDENT>def get_root_locations(self):<DEDENT>
return<EOL>
Gets the root location in the location hierarchy.

        A location with no parents is an orphan. While all location
        ``Ids`` are known to the hierarchy, an orphan does not appear in
        the hierarchy unless explicitly added as a root location or
        child of another location.

        :return: the root locations
        :rtype: ``osid.mapping.LocationList``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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