code: public static void normalizeQuotes(final List<Token> sentence,
        final String lang) {
  
      for (final Token token : sentence) {
        if (lang.equalsIgnoreCase("en")) {
          token.setTokenValue(
              leftSingleQuote.matcher(token.getTokenValue()).replaceAll("`"));
          token.setTokenValue(
              rightSingleQuote.matcher(token.getTokenValue()).replaceAll("'"));
          token.setTokenValue(
              leftDoubleQuote.matcher(token.getTokenValue()).replaceAll("``"));
          token.setTokenValue(
              rightDoubleQuote.matcher(token.getTokenValue()).replaceAll("''"));
        } else if (lang.equalsIgnoreCase("ca") || lang.equalsIgnoreCase("de")
            || lang.equalsIgnoreCase("es") || lang.equalsIgnoreCase("eu")
            || lang.equalsIgnoreCase("fr") || lang.equalsIgnoreCase("gl")
            || lang.equalsIgnoreCase("it") || lang.equalsIgnoreCase("nl")
            || lang.equalsIgnoreCase("pt") || lang.equalsIgnoreCase("ru")) {
          token.setTokenValue(
              toAsciiSingleQuote.matcher(token.getTokenValue()).replaceAll("'"));
          token.setTokenValue(
              toAsciiDoubleQuote.matcher(token.getTokenValue()).replaceAll("\""));
        }
      }
    }
docs: Normalizes non-ambiguous quotes according to language and corpus.
  
  @param sentence
  the list of tokens
  @param lang
  the language