code: func NewPlural(src string) (Plural, error) {
  	switch src {
  	case "zero":
  		return Zero, nil
  	case "one":
  		return One, nil
  	case "two":
  		return Two, nil
  	case "few":
  		return Few, nil
  	case "many":
  		return Many, nil
  	case "other":
  		return Other, nil
  	}
  	return Invalid, fmt.Errorf("invalid plural category %s", src)
  }
docs: // NewPlural returns src as a Plural
  // or Invalid and a non-nil error if src is not a valid Plural.