relax feedback requirement
@@ -70,10 +70,6 @@ pub trait LoopVariable<'a, G: Scope, T: Timestamp> {
impl<G: Scope> Feedback<G> for G {
fn feedback<D: Data>(&mut self, summary: <G::Timestamp as Timestamp>::Summary) -> (Handle<G, D>, Stream<G, D>) {
- if summary == Default::default() {
- panic!("Cannot use default summary for a loop variable");
- }
-
let mut builder = OperatorBuilder::new("Feedback".to_owned(), self.clone());
let (output, stream) = builder.new_output();
