// storage class kind supported.
func IsValid(sc string) bool {
	return sc == RRS || sc == STANDARD
}

// UnmarshalText unmarshals storage class from its textual form into
// storageClass structure.
func (sc *StorageClass) UnmarshalText(b []byte) error {
	scStr := string(b)
	if scStr == "" {
		return nil
	}
	s, err := parseStorageClass(scStr)
	if err != nil {
		return err