code: func (api *API) UpdateArgoSmartRouting(zoneID, settingValue string) (ArgoFeatureSetting, error) {
  	if !contains(validSettingValues, settingValue) {
  		return ArgoFeatureSetting{}, errors.New(fmt.Sprintf("invalid setting value '%s'. must be 'on' or 'off'", settingValue))
  	}
  
  	uri := "/zones/" + zoneID + "/argo/smart_routing"
  
  	res, err := api.makeRequest("PATCH", uri, ArgoFeatureSetting{Value: settingValue})
  	if err != nil {
  		return ArgoFeatureSetting{}, errors.Wrap(err, errMakeRequestError)
  	}
  
  	var argoDetailsResponse ArgoDetailsResponse
  	err = json.Unmarshal(res, &argoDetailsResponse)
  	if err != nil {
  		return ArgoFeatureSetting{}, errors.Wrap(err, errUnmarshalError)
  	}
  	return argoDetailsResponse.Result, nil
  }
docs: // UpdateArgoSmartRouting updates the setting for smart routing.
  //
  // API reference: https://api.cloudflare.com/#argo-smart-routing-patch-argo-smart-routing-setting