Koltin map string to sequence of chars with previous ones. #kotlin loop with previous

.kt

fun String.withPrevious(): Sequence<Element> {
    val string = this
    return sequence {
        for (i in string.indices) {
            val current = string[i]
            val previous = if (i > 0) string[i - 1] else null
            yield(Element(current, previous))
        }
    }
}

data class Element (
    val current: Char,
    val previous: Char?
)