cfg.Enable = env.Get(EnvEnable, kvs.GetWithDefault(Enable, DefaultKVS)) == config.EnableOn

	if d := env.Get(EnvBlockSize, kvs.GetWithDefault(BlockSize, DefaultKVS)); d != "" {
		objectSize, err := humanize.ParseBytes(d)
		if err != nil {
			return cfg, err
		}
		cfg.BlockSize = int64(objectSize)
	}

	cfg.Endpoint = env.Get(EnvEndpoint, kvs.GetWithDefault(Endpoint, DefaultKVS))

	// The returned value can no longer be modified once returned.
	// Should be set before calling Get().
	updateFn func() (T, error)

	// ttl for a cached value.
	ttl time.Duration

	opts Opts

	// Once can be used to initialize values for lazy initialization.
	// Should be set before calling Get().
	Once sync.Once

	// Managed values.
	valErr atomic.Pointer[struct {
		v T
		e error
	}]