Implement the following function as a new function for the linked list toolkit. (Use the usual node definition with member variables called data and link. The data field is an int.) int product(const node* head_ptr);//Precondition: head_ptr is the head pointer of a linked list.//The list might be empty or it might be non-empty.//Postcondition: The return value is the product of all the data components//of all the node