val nums = generateSequence(1) { x -> x + 3 }

val fibs = sequence {
    var a = 1; var b = 1
    yield(a)
    while (true) {
        yield(b)
        val c = a
        a = b; b += c
    }
}

fun main() {
    println(nums.take(10).toList())
    println(fibs.take(10).toList())
}