def get_equivalent_objective_query(self):
raise errors.Unimplemented()<EOL>
Gets the query for an equivalent objective.

        Multiple retrievals produce a nested ``OR`` term.

        return: (osid.learning.ObjectiveQuery) - the objective query
        raise:  Unimplemented -
                ``supports_equivalent_objective_query()`` is ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_equivalent_query()`` is ``true``.*