一些看似奇怪的代码

// NewRequest constructs a request
// Convert payload to a JSON
func (c *ActClient) NewRequest(method, url string, payload interface{}) (*http.Request, error) {
	var buf io.Reader
	if payload != nil {
		var b []byte
		b, err := json.Marshal(&payload)
		if err != nil {
			return nil, err
		}
		buf = bytes.NewBuffer(b)
	}
	return http.NewRequest(method, url, buf)
}

if response.StatusCode/2 != 100 {
    return "", fmt.Errorf("gtp api %s", response.Status)
}