code: def tag_crf(self, untagged_string: str):
          
          untagged_tokens = wordpunct_tokenize(untagged_string)
          pickle_path = self.available_taggers['crf']
          tagger = CRFTagger()
          tagger.set_model_file(pickle_path)
          tagged_text = tagger.tag(untagged_tokens)
          return tagged_text
docs: Tag POS with CRF tagger.
          :type untagged_string: str
          :param : An untagged, untokenized string of text.
          :rtype tagged_text: str