code: def put_request_payment(self, bucket, payer):
          
          data = RequestPayment(payer).to_xml()
          details = self._details(
              method=b"PUT",
              url_context=self._url_context(bucket=bucket, object_name="?requestPayment"),
              body=data,
          )
          d = self._submit(self._query_factory(details))
          return d
docs: Set request payment configuration on bucket to payer.
  
          @param bucket: The name of the bucket.
          @param payer: The name of the payer.
          @return: A C{Deferred} that will fire with the result of the request.