protected function _format($statusCode=null, $message=null, $body=false)
    {
        $format = [];
        // Status Code field is necessary
        $format['code'] = ($statusCode) 
            ?: $this->response->getStatusCode();
        // Message field
        if ($message) {
            $format['message'] = $message;
        }
        // Body field
        if ($body !== false) {
            $format['data'] = $body;
        }
        
        return $format;
    }