NodeT *insertLL(NodeT *list, int d) {
   NodeT *new = makeNode(d);  // create new list element
   new->next = list;          // link to beginning of list
   return new;                // new element is new head
}

NodeT *deleteHead(NodeT *list) {
   assert(list != NULL);  // ensure list is not empty
   NodeT *head = list;    // remember address of first element
   list = list->next;     // move to second element
   free(head);
   return list;           // return pointer to second element
}