code: def available_languages(self):
          
          available_languages = getattr(self, '_available_languages', None)
          if available_languages:
              return available_languages
          try:
              languages = os.listdir(self.data_directory)
          except OSError:
              raise StopWordError(
                  "'datas' directory is unreadable, check your installation.")
          languages = sorted(map(lambda x: x.replace('.txt', ''), languages))
          setattr(self, '_available_languages', languages)
          return languages
docs: Returns a list of languages providing collection of stop words.