*& head code example
Example: struct Node** head_ref
void insert(node** head, int value) { node* new_node = new node node *last = *head; new_node->data = value; new_node->next = NULL; if (*head == NULL) { *head = new_node; return; } while (last->next != NULL) last = last->next; last->next = new_node; return; }