Function delay 

pub fn delay(
    core: &Core,
    binding: &Arc<dyn ProducerBinding>,
    source: NodeId,
    ms: u64,
) -> NodeId

Delays each upstream DATA by ms milliseconds. Multiple values can be in-flight simultaneously, each with its own timer.

• COMPLETE waits for all pending delays, then completes.
• ERROR cancels all pending and propagates immediately.