void que_insert(QueueADT queue, void *data) {
    // create node w/ data
    Node* n;
    n = malloc(sizeof(n));
    n->next = NULL;
    n->previous = NULL;
    n->data = data;

    // if compare function doesn't exist, place in front of queue
    if(queue->cmp == NULL) {
        n->next = queue->front;
        queue->front->previous = n;
        queue->front = n;
        return;
    }

    // if empty queue
    if(queue->length == 0) {
        // assign front and back to given node
        printf(": first insert \n");
        queue->front = n;
        queue->back = n;
    } else {
        Node* curr = queue->front;
        int first = 1;

        while(1) {
            // if < first node in queue, reassign head
            if(first && queue->cmp(data, curr->data) < 0) {
                printf(": first %ld %ld\n", (long int)data, (long int)curr->data);
                queue->front->previous = n;
                n->next = queue->front;
                queue->front = n;

                printf("{\n  next: %ld,\n  prev: NULL\n}\n\n",
                    (long int)n->next->data);
                break;
            } else if(curr->next == NULL){
                // if > end reassign tail
                printf(": end\n");
                queue->back->next = n;
                n->previous = queue->back;
                queue->back = n;

                printf("{\n  next: NULL,\n  prev: %ld\n}\n\n",
                   (long int)n->previous->data);
                break;
            } else if(queue->cmp(data, curr->next->data) < 0){
                // if middle check if next is less
                printf(": middle \n");
                n->next = curr;
                n->previous = curr->previous;
                curr->previous = n;

                printf("{\n  next: %ld,\n  prev: %ld\n}\n\n",
                    (long int)n->next->data, (long int)n->previous->data);
                break;
            }

            first = 0;
            curr = curr->next;
        }
        printf("insert success\n");
    }
    queue->length++;
}