With imperative programming, we have the ability to access the n^th element of any array/list, which is quite a common requirement. The elementAt operator is really helpful in this regard; it pulls the n^th element from the producer and emits it as its own sole emission.

Take a look at the following piece of code:

    fun main(args: Array<String>) { 
      val observable = listOf(10,1,2,5,8,6,9) 
        .toObservable() 
 
      observable.elementAt(5)//(1) 
        .subscribe { println("Received $it") } 
 
      observable.elementAt(50)//(2) 
        .subscribe { println("Received $it") } 
    } 

Take a look at the following output before we continue to inspect the code:

On comment (1), we requested the 5^th element from Observable, and it emitted the same (count starts with zero). However, on comment (2), we requested the 50^th element, which doesn't even exist in Observable, so it didn't emit anything.

This operator achieves this behavior with the help of the Maybe monad, which will be covered later.