fun <T> Sequence<T>.repeat() = object : Iterator<T> {
    var iterator = this@repeat.iterator()
    
    override fun next(): T {
        val result = iterator.next()
        if (!iterator.hasNext()) {
            iterator = this@repeat.iterator()
        }
        return result
    }

    override fun hasNext() = iterator.hasNext()
}.asSequence()


fun main(args: Array<String>) {
    sequenceOf(1, 2, 3).repeat().take(6).forEach { println(it) }
}