lastIndexOf
Returns last index of element, or -1 if the sequence does not contain element.
fun <T> Sequence<T>.lastIndexOf(element: T): Int(source)
fun main() {
val seq = sequenceOf("apple", "banana", "cherry", "banana")
val index = seq.lastIndexOf("banana")
println("Last index of 'banana' is $index") // prints: Last index of 'banana' is 3
}