XBT_PUBLIC(int) xbt_lib_add_level(xbt_lib_t lib, void_f_pvoid_t free_f);
XBT_PUBLIC(void) xbt_lib_set(xbt_lib_t lib, const char *name, int level,
void *obj);
+XBT_PUBLIC(void) xbt_lib_unset(xbt_lib_t lib, const char *key, int level, int invoke_callback);
XBT_PUBLIC(void *) xbt_lib_get_or_null(xbt_lib_t lib, const char *name,
int level);
XBT_PUBLIC(xbt_dictelm_t) xbt_lib_get_elm_or_null(xbt_lib_t lib, const char *key);