sub _respond {
  my($heap, $request_id, $request) = @_;
  my $response = $request->[REQ_RESPONSE];
  if ($heap->{frmax}) {
    if ($heap->{redir}->{$request_id}->{followed}) {
      # ...
    }
    else {
      my $tmpresponse = $response;
      while (defined ...) {
        my $prev = $heap->{redir}->{$request_id}->{from};
        $tmpresponse->previous(...);
        $tmpresponse = $tmpresponse->previous();
        $request_id = $prev;
      }
    }
  }
  $request->[REQ_POSTBACK]->($response);
}