def atomize_week_date(input, separator, sign)
      date = parse(input)
      sign = "#{sign}1".to_i
      @separator = separator

      [sign * date.year, date.month, date.day]
    end
def atomize_week_date(input, separator, sign)
      date = parse(input)
      sign = "#{sign}1".to_i
      @separator = separator

      [sign * date.year, date.month, date.day]
    end
Parses a week date (YYYY-Www-D, YYYY-Www) and returns its atoms.

 @param [String] input the date string.
 @param [String] separator the separator found in the input.
 @param [String] sign the sign found in the input.

 @return [Array<Integer>] date atoms.