code: func (o *EnvOptions) Validate() error {
  	if len(o.Filenames) == 0 && len(o.resources) < 1 {
  		return fmt.Errorf("one or more resources must be specified as <resource> <name> or <resource>/<name>")
  	}
  	if o.List && len(o.output) > 0 {
  		return fmt.Errorf("--list and --output may not be specified together")
  	}
  	if len(o.Keys) > 0 && len(o.From) == 0 {
  		return fmt.Errorf("when specifying --keys, a configmap or secret must be provided with --from")
  	}
  	return nil
  }
docs: // Validate makes sure provided values for EnvOptions are valid