public function setRacy($value = null)
    {
        switch ($value) {
            case 'include':
                $this->_params['racy'] = $value;
                break;
            case 'exclude':
                $this->_params['racy'] = $value;
                break;
            case null:
                unset($this->_params['racy']);
                break;
        }
        return $this;
    }