code: def processQueryString(self, s):
      
      char_blacklist = set(string.punctuation)
      char_blacklist.remove("'")
      char_blacklist.remove("&")
      char_blacklist = frozenset(char_blacklist)
      return __class__.unpunctuate(s.lower(), char_blacklist=char_blacklist)
docs: See CoverSource.processQueryString.