docs: def _send_request(self):
          """
          Sends the request to the backend.
          """
          if isinstance(self._worker, str):
              classname = self._worker
          else:
              classname = '%s.%s' % (self._worker.__module__,
                                     self._worker.__name__)
          self.request_id = str(uuid.uuid4())
          self.send({'request_id': self.request_id, 'worker': classname,
                     'data': self._args})