def get_roots(self):
        """Gets the root nodes of this hierarchy.

        return: (osid.id.IdList) - the root nodes
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        *compliance: mandatory -- This method must be implemented.*

        """
        id_list = []
        for r in self._rls.get_relationships_by_genus_type_for_source(self._phantom_root_id, self._relationship_type):
            id_list.append(r.get_destination_id())
        return IdList(id_list)
def get_roots ( self ) : id_list = [ ] for r in self . _rls . get_relationships_by_genus_type_for_source ( self . _phantom_root_id , self . _relationship_type ) : id_list . append ( r . get_destination_id ( ) ) return IdList ( id_list )
Gets the root nodes of this hierarchy.

        return: (osid.id.IdList) - the root nodes
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        *compliance: mandatory -- This method must be implemented.*