code: function ParseNationalNumber(number, md) {
      if (!md.possiblePattern.test(number) ||
          !md.nationalPattern.test(number)) {
        return null;
      }
      // Success.
      return new NationalNumber(md, number);
    }
docs: Parse a national number for a specific region. Return null if the number is not a valid national number (it might still be a possible number for parts of that region).