``` val increment = "Increment" val decrement = "D...

# android

[jw]

val increment = "Increment"
val decrement = "Decrement"
val actions = Observable.from(increment, increment, decrement, decrement);
val states = actions.scan(0, (action, state) -> when(action) {
  is increment -> state + 1
  is decrement -> state - 1
  else -> throw IllegalArgumentException("Unknown action $action")
})
states.subscribe(state -> println(state))

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