public static SinglyLinkedListNode removeDuplicates(SinglyLinkedListNode llist) {
        SinglyLinkedListNode current = llist;
        
        while (current != null && current.next != null) {
            if (current.data == current.next.data) {
                current.next = current.next.next;
            } else {
                current = current.next;
            }
        }
        
        return llist;
    }