events.cacheMap { x -> Value in
    // Closure executed once per unique `x`, replayed when not unique.
    expensiveOperation(x)
}

events.cacheMap(whenExceeding: .seconds(1)) { x -> Value in
    // Closure executed once per unique `x`, replayed when operation of unique value took 
    // longer than specified duration.
    expensiveOperation(x)
}

events.cacheFlatMap(cache: .memoryRefreshingAfter()) { x -> AnyPublisher<Expiring<Value>, Failure> in
    // Closure executed once per unique `x`, replayed when input not unique. Cache 
    // invalidated when date returned is greater than or equal to date of map execution.
    expensiveOperation(x).map { output in 
        Expiring(
            value: output,
            expiration: Date() + hours(1)
        )
    }
}

// Use your own cache or the included .memory and .disk stores.
events.cacheMap(cache: MyCache()) { x -> Value in
    expensiveOperation(x)
}