C++ Doubly Linked List

Using the following information, please help write a recursive function that will copy the list. Helper functions are allowed for recursion, but you must use the required function prototype.

This is a doubly linked list designed as follows:

struct node { int data; node * previous; node * next; }; void duplicate (node *& newHead) const recursively create a copy of the source list with head. newhead is the head of the destination list