doseq and for but for streams

Dart has await for to iterate over streams, we don’t have anything like this.
.forEach is less powerful (you can await inside an await for and it will pause/resume the subscription.
dostream would be like doseq but for streams (potentially mixed with some seqables) and await-for would be like but but would evaluate to a stream.
Both are poor names:

• dostream would implicitely await the whole iteration to be over
• await-for would not await as it would return a stream...
  So await-doseq and stream-for instead?

Start by reading the existing doseq and but implementations, then compare their behavior with Dart's await for and streams. Clarify whether await-doseq and stream-for are the desired names and semantics; the issue is complete only after that design is settled and the corresponding stream iteration behavior is implemented.