a few dll functions

template <typename T>
// checks if list is empty
bool TList<T>::IsEmpty() const { return size == 0; }

template <typename T>
void TList<T>::InsertFront(const T& d) {
    // create node to insert
    Node<T>* node = new Node<T>(d);
    // check if list is empty
    if (IsEmpty()) { first = last = node; }
    else {
        // set prev for new first node
        node->prev = nullptr;
        // set prev for old first node
        first->prev = node;
        // set next for new first node
        node->next = first;
        // set first to new first node
        first = node;
    }
    size++;
}

template <typename T>
// returns data from first node
T& TList<T>::GetFirst() const {
    // if there's nothing to get, return dummy
    if (size == 0) { return dummy; }
    // else return data
    else { return first->data; }
}