code: public static String isbn10Format(final String pstring) {
      if (pstring == null) {
        return null;
      }
      final ValueWithPos<String> formatedValue = isbn10FormatWithPos(new ValueWithPos<>(pstring, -1));
      return formatedValue.getValue();
    }
docs: format isbn10 with separator signs.
  
  @param pstring string to format
  @return formated string