code: def _setup_language_variables(self, lang: str):  # pragma: no cover
          
          assert lang in PUNCTUATION.keys(), \
              'Sentence tokenizer not available for {0} language.'.format(lang)
          internal_punctuation = PUNCTUATION[lang]['internal']
          external_punctuation = PUNCTUATION[lang]['external']
          file = PUNCTUATION[lang]['file']
          tokenizer_path = os.path.join(os.path.expanduser(self._get_models_path(language=lang)),
                                        file)
          assert os.path.isfile(tokenizer_path), \
              'CLTK linguistics data not found for language {0} {}'.format(lang)
          return internal_punctuation, external_punctuation, tokenizer_path
docs: Check for language availability and presence of tokenizer file,
          then read punctuation characters for language and build tokenizer file
          path.
          :param lang: The language argument given to the class.
          :type lang: str
          :rtype (str, str, str)