filterIndexedTo

@IgnorableReturnValueinline fun <C : Appendable> CharSequence.filterIndexedTo(destination: C, predicate: (index: Int, Char) -> Boolean): C(source)

fun main() {
    val source = "Kotlin 1.8.20"
    val destination = StringBuilder()

    // Append only the characters that are at odd indices
    source.filterIndexedTo(destination) { index, ch ->
        index % 2 == 1
    }

    println(destination.toString())   // prints the filtered characters
}