Cancel the stream.
Method pulls elements from stream and returns future that:
- fails if stream is failed
- completes with None in case if stream is completed
- completes with Some(element)
in case next element is available from stream.
Method pulls elements from stream and returns future that:
- fails if stream is failed
- completes with None in case if stream is completed
- completes with Some(element)
in case next element is available from stream.
This trait adds cancel support to SinkQueue.