//Insert "it" at current position

void insert(const E& it)

{

curr->next = curr->next->prev =

new Link<E>(it, curr, curr->next);

cnt++;

}

//append "it" to the end of the list

void append(const E& it)

{

tail->prev = tail->prev->next =

new Link<E>(it,tail->prev,tail);

cnt++;

}

//remove and return current element

E remove()

{

if (curr->next == tail)

return NULL;

E it = curr->next->element;

Link<E>* ltemp = curr->next;

curr->next->next=>prev = curr;

curr->next = curr->next->next;

delete ltemp;

cnt--;

return it;

}

//move fence one step left; no change if left is empty

void prev()

{

if (curr != head)

curr = curr->prev;

}