void xbt_lib_unset(xbt_lib_t lib, const char *key, int level, int invoke_callback)
{
void **elts = xbt_dict_get_or_null(lib->dict, key);
void xbt_lib_unset(xbt_lib_t lib, const char *key, int level, int invoke_callback)
{
void **elts = xbt_dict_get_or_null(lib->dict, key);