code: func (r FutureSubmitBlockResult) Receive() error {
  	res, err := receiveFuture(r)
  	if err != nil {
  		return err
  	}
  
  	if string(res) != "null" {
  		var result string
  		err = json.Unmarshal(res, &result)
  		if err != nil {
  			return err
  		}
  
  		return errors.New(result)
  	}
  
  	return nil
  
  }
docs: // Receive waits for the response promised by the future and returns an error if
  // any occurred when submitting the block.