docs: def get_root_catalogs(self):
          """Gets the root catalogs in the catalog hierarchy.
  
          A node with no parents is an orphan. While all catalog ``Ids``
          are known to the hierarchy, an orphan does not appear in the
          hierarchy unless explicitly added as a root node or child of
          another node.
  
          return: (osid.cataloging.CatalogList) - the root catalogs
          raise:  OperationFailed - unable to complete request
          raise:  PermissionDenied - authorization failure
          *compliance: mandatory -- This method is must be implemented.*
  
          """
          # Implemented from template for
          # osid.resource.BinHierarchySession.get_root_bins
          if self._catalog_session is not None:
              return self._catalog_session.get_root_catalogs()
          return CatalogLookupSession(
              self._proxy,
              self._runtime).get_catalogs_by_ids(list(self.get_root_catalog_ids()))