Insert(int newData){

    NodeT * current, *follow, *tmp;

    tmp = new NodeT;
    tmp->data = newData

    if (head == nullptr or head->data > newData) {
       t->next = head
       head = t;
    } else {
       current = head->next;
       follow = head;

       while (current != nullptr and current->data < newData) {
           follow = current;
           current = current->next;
       }
       tmp ->next = current;
       follow->next = tmp;
    }
}
// delete a node.

follow->next = current->next;
delete current;