code: def _clean_text(self, text):
          
          clean = []
          for char in text:
              if char in self.punc_stops:
                  clean += '.'
              elif char not in self.punc:
                  clean += char
              else:
                  pass
          return (''.join(clean)).lower()
docs: Clean the text of extraneous punction.
  
          By default, ':', ';', and '.' are defined as stops.
          :param text: raw text
          :return: clean text
          :rtype : string