docs: def clean_url(self):
          """Only clean the url params and return self."""
          raw_url = self.request['url']
          parsed_url = urlparse(raw_url)
          qsl = parse_qsl(parsed_url.query)
          for qs in qsl:
              new_url = self._join_url(parsed_url,
                                       [i for i in qsl if i is not qs])
              new_request = deepcopy(self.request)
              new_request['url'] = new_url
              self._add_task('qsl', qs, new_request)
          return self