code: func (e Enum) Choices() string {
  	keys := make([]string, 0, len(e))
  	for k := range e {
  		if k == "" {
  			k = `""`
  		}
  		keys = append(keys, k)
  	}
  	sort.Strings(keys)
  	return strings.Join(keys, ", ")
  }
docs: // Choices returns a comma-separated string listing sorted enumeration choices.