@utilities.remove_null_proxy_kwarg<EOL><INDENT>def get_vault_hierarchy_design_session(self):<DEDENT>
if not self.supports_vault_hierarchy_design():<EOL><INDENT>raise errors.Unimplemented()<EOL><DEDENT>return sessions.VaultHierarchyDesignSession(runtime=self._runtime)<EOL>
Gets the session designing vault hierarchies.

        return: (osid.authorization.VaultHierarchyDesignSession) - a
                ``VaultHierarchyDesignSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_vault_hierarchy_design() is
                false``
        *compliance: optional -- This method must be implemented if
        ``supports_vault_hierarchy_design()`` is true.*