Exmld.KinesisStage.handle_demand

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handle_demand(incoming_demand, state)

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Handle subscriber demand.

Return up to incoming_demand + pending_demand events, fetching (from state) as needed, and storing in state any excess. If not enough events are available, record unsatisfied demand in state, and then return those events when answering a subsequent call. See the QueueBroadcaster example in GenStage for an explanation of this demand queueing behavior.