code: func (r *GoRequest) Get(key int) (value interface{}, err error) {
  	switch key {
  	case HTTP_SERVER_HEADER:
  		value = r.GetHeader()
  	case HTTP_MULTIPART_FORM:
  		value, err = r.GetMultipartForm()
  	case HTTP_QUERY:
  		value = r.Original.URL.Query()
  	case HTTP_FORM:
  		value, err = r.GetForm()
  	case HTTP_REQUEST_URI:
  		value = r.Original.URL.String()
  	case HTTP_REQUEST_CONTEXT:
  		value = r.Original.Context()
  	case HTTP_REMOTE_ADDR:
  		value = r.Original.RemoteAddr
  	case HTTP_METHOD:
  		value = r.Original.Method
  	case HTTP_PATH:
  		value = r.Original.URL.Path
  	case HTTP_HOST:
  		value = r.Original.Host
  	case HTTP_URL:
  		value = r.Original.URL
  	case HTTP_BODY:
  		value = r.Original.Body
  	default:
  		err = ENGINE_UNKNOWN_GET
  	}
  
  	return
  }
docs: // Communicate with the server engine to exchange data