code: func (p *PullPolicy) Set(v string) error {
  	switch v {
  	case "always":
  		*p = PullAlways
  	case "never":
  		*p = PullNever
  	case "if-not-present":
  		*p = PullIfNotPresent
  	default:
  		return fmt.Errorf("invalid value %q, valid values are: always, never or if-not-present", v)
  	}
  	return nil
  }
docs: // Set implements the Set() function of pflags.Value interface
  // The valid options are "always", "never" or "if-not-present"