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kotlinlang

Hi there. I'm looking for a _way_ to collect `Observable`'s emissions in bundles of data, some sort of history of the last values. I know it sound like `buffer()` operator, but I just can't get it right.

When having `A`, `B`, `C`, `D`, `E`, `F` emitted one after another with some delay, I would like to have an `Observable` emitting: `[A]`, `[A, B]`, `[A,B,C]`, `[B, C, D]`, `[C, D, E]`, `[D, E, F]`. We are only interested in last values, so I suppose, we could use here a `Flowable`.

Thanks.

You could use `.scan` and use some kind of queue/stack structure like `Deque` as the accumulator

I've had to implement this multiple times unfortunately. Really what you're looking for is `combineLatest` but that emits a tuple or whatever with null values until every stream has emitted