map_val_t ll_lookup (list_t *ll, map_key_t key);
map_val_t ll_remove (list_t *ll, map_key_t key);
size_t ll_count (list_t *ll);
map_val_t ll_lookup (list_t *ll, map_key_t key);
map_val_t ll_remove (list_t *ll, map_key_t key);
size_t ll_count (list_t *ll);