link_t* list_new(int value);
link_t* list_append(link_t* head, int value);
link_t* list_prepend(link_t* head, int value);
+link_t* list_insert(link_t* head, unsigned index, int value);
+link_t* list_delete(link_t* head, unsigned index);
unsigned list_count(link_t* head);
void list_set(link_t* head, unsigned index, int value);
int list_get(link_t* head, unsigned index);