ruby_register_rollback_func_for_ensure 4404 hash.c             ruby_register_rollback_func_for_ensure(hash_foreach_ensure, hash_foreach_ensure_rollback);
ruby_register_rollback_func_for_ensure  910 internal.h     void ruby_register_rollback_func_for_ensure(VALUE (*ensure_func)(ANYARGS), VALUE (*rollback_func)(ANYARGS));