Implement in C++ a doubly linked list using two dummy nodes (one for the head and one for the tail). The code must contain a ListNode, List, and Listltr class

The code for the copy constructor and the operator()= method are shown below

List::List(const List& source) t Copy Constructor head new ListNode; tail new ListNode; head next tail; tail previous head; count 0; List It r iter (source head->next) while (liter isPastEnd deep copy of the list insert AtTail(iter.retrieve iter.moveForward List& List operator (const List& source) //Equals operator if this &source) return this; else t make Empty Listitr iter (source. head- next); while (liter. is PastEnd insertAtTail(iter. retrieve iter. moveForward return this