code: func AddReturnRule(chain string) error {
  	var (
  		table = Filter
  		args  = []string{"-j", "RETURN"}
  	)
  
  	if Exists(table, chain, args...) {
  		return nil
  	}
  
  	err := RawCombinedOutput(append([]string{"-A", chain}, args...)...)
  	if err != nil {
  		return fmt.Errorf("unable to add return rule in %s chain: %s", chain, err.Error())
  	}
  
  	return nil
  }
docs: // AddReturnRule adds a return rule for the chain in the filter table