code: private boolean isNumbering(int i, AnalyzedTokenReadings[] tokens) {
      return i >= 2
              && StringUtils.equalsAny(tokens[i-1].getToken(), ")", "]")
              && NUMERALS_EN.matcher(tokens[i-2].getToken()).matches()
              && !(i > 3 && tokens[i-3].getToken().equals("(")
                && tokens[i-4].hasPosTagStartingWith("SUB:")); // no numbering "Der Vater (51) fuhr nach Rom."
    }
docs: e.g. "a) bla bla"