doseq and for but for streams

[cgrand]

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?