code: func ConvertUnitsString(val string, from Unit, to Unit) (float64, error) {
  	floatValue, err := strconv.ParseFloat(val, 64)
  	if err != nil {
  		return 0, err
  	}
  	return ConvertUnits(floatValue, from, to), nil
  }
docs: // ConvertUnitsString converts the given string value in the base Unit to the given new Unit.