fun removeDuplicates(llist: SinglyLinkedListNode?): SinglyLinkedListNode? {
    // Write your code here
    var currentNode = llist
    var firstNode = llist
    while (currentNode != null){
        //println("Current Node: ${nextNode.data}")
        //println("Next Node: ${nextNode.next!!.data}")
       if (currentNode.next != null &&  currentNode.next!!.data == currentNode.data){
           // duplicate, remove it
           var temp = currentNode.next
           currentNode.next = currentNode.next!!.next
           temp = null
       } else {
         currentNode = currentNode.next 
       }
    }
       // println("End")
    //printSinglyLinkedList(firstNode, " ")
    return firstNode

}