code: def build_concordance(text_str: str) -> List[List[str]]:
      
      punkt_vars = PunktLanguageVars()  # type: PunktLanguageVars
      orig_tokens = punkt_vars.word_tokenize(text_str)  # type: List[str]
      concordance_index = ConcordanceIndex(orig_tokens)  # type: Any
      #! rm dupes after index, before loop
      tokens_set = set(orig_tokens)  # type: Set[str]
      punct_list = [',', '.', ';', ':', '"', "'", '[', ']']  # type: List[str]
      # this needs to be changed or rm'ed
      tokens = [x for x in tokens_set if x not in punct_list]  # List[str]
      index = concordance_index.return_concordance_all(tokens)  # List[List[str]]
      return index
docs: Inherit or mimic the logic of ConcordanceIndex() at:
       http://www.nltk.org/_modules/nltk/text.html
      and/or ConcordanceSearchView() & SearchCorpus() at:
       https://github.com/nltk/nltk/blob/develop/nltk/app/concordance_app.py
      :param text_string: Text to be turned into a concordance
      :type text_string: str
      :return: list