type iSdl interface {
GetAll(string) ([]string, error)
SetIfNotExists(ns string, key string, data interface{}) (bool, error)
+ Get(string, []string) (map[string]interface{}, error)
+ SetIf(ns string, key string, oldData, newData interface{}) (bool, error)
+ Set(ns string, pairs ...interface{}) error
}