code: private static String replacePunctuation(String lemma) {
          lemma = lemma.replace(",", " , ");
          lemma = lemma.replace('.', ' ');
  //        lemma = lemma.replace('-', ' ');
          lemma = lemma.replace('\'', ' ');
          lemma = lemma.replace('(', ' ');
          lemma = lemma.replace(')', ' ');
          lemma = lemma.replace(':', ' ');
          lemma = lemma.replace(";", " ; ");
          return lemma;
      }
docs: Replaces punctuation by spaces.
  
  @param lemma input string
  @return string with spaces in place of punctuation