3. The node class has been defined as follows: template public: // TYPEDEF typedef Item value type: // CONSTRUCTOR node const Item& init data= Item( ), node* init link=NULL ) fdata field -init data: 1link field- init link; // MODIFICATION MEMBER FUNCTIONS Item& data() 1 return data field; h node* link( ) return link field; h void set data(const Item& new data) { data field = new data void set link(node * new link) { link field = new link; // CONST MEMBER FUNCTIONS const Item& dataconst return data field const node* linkconst return link field private: Item data field node *link_field; Write the implementation of a const forward iterator for this class