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.)

void list_tail_insert(node* head_ptr, const node::value_type& entry);

// Precondition: head_ptr is the head pointer of a non-empty linked list.

// Postcondition: A new node has been added at the tail end

// of the list. The data in the new node is taken from the parameter called entry.