func NewResourceVersionConflictsError(key string, rv int64) *StorageError {
	return &StorageError{
		Code:            ErrCodeResourceVersionConflicts,
		Key:             key,
		ResourceVersion: rv,
	}
}

func NewUnreachableError(key string, rv int64) *StorageError {
	return &StorageError{
		Code:            ErrCodeUnreachable,
		Key:             key,
		ResourceVersion: rv,
	}
}

func NewTimeoutError(key, msg string) *StorageError {