public function setExists($exists)
    {
        if ($exists instanceof Zend_Config) {
            $exists = $exists->toArray();
        }

        if (is_array($exists)) {
            if (isset($exists['exists'])) {
                $exists = (boolean) $exists['exists'];
            }
        }

        $this->_exists = (boolean) $exists;
        return $this;
    }