working on List

map.go

@@ -1,6 +1,7 @@
 package storage
 
 import (
+	"errors"
 	"fmt"
 )
 
@@ -28,6 +29,10 @@ func (m *Map) Close() error {
 	return nil
 }
 
+func (m *Map) List(ns []string, limits ...string) ([]string, error) {
+	return nil, errors.New("not impl")
+}
+
 func (m *Map) Get(key string, ns ...string) ([]byte, error) {
 	namespace := resolveNamespace(ns)
 	if _, ok := (*m)[namespace]; !ok {