Services_JSON::isError

    function isError($data, $code = null)
    {
        _deprecated_function( __METHOD__, '5.3.0', 'The PHP native JSON extension' );

        if (class_exists('pear')) {
            return PEAR::isError($data, $code);
        } elseif (is_object($data) && (get_class($data) == 'services_json_error' ||
                                 is_subclass_of($data, 'services_json_error'))) {
            return true;
        }

        return false;
    }