code: func (call *GetUserRichMenuCall) Do() (*RichMenuResponse, error) {
  	endpoint := fmt.Sprintf(APIEndpointGetUserRichMenu, call.userID)
  	res, err := call.c.get(call.ctx, endpoint, nil)
  	if err != nil {
  		return nil, err
  	}
  	defer closeResponse(res)
  	return decodeToRichMenuResponse(res)
  }
docs: // Do method