def get_hierarchies(self):
<EOL>if self._catalog_session is not None:<EOL><INDENT>return self._catalog_session.get_catalogs()<EOL><DEDENT>collection = JSONClientValidated('<STR_LIT>',<EOL>collection='<STR_LIT>',<EOL>runtime=self._runtime)<EOL>result = collection.find().sort('<STR_LIT>', DESCENDING)<EOL>return objects.HierarchyList(result, runtime=self._runtime, proxy=self._proxy)<EOL>
Gets all hierarchies.

        In plenary mode, the returned list contains all known
        hierarchies or an error results. Otherwise, the returned list
        may contain only those hierarchies that are accessible through
        this session.

        return: (osid.hierarchy.HierarchyList) - a list of
                ``Hierarchies``
        raise:  OperationFailed - unable to complete request
        raise:  PermissionDenied - authorization failure
        *compliance: mandatory -- This method must be implemented.*