Create dbstream interface

db.go

@@ -2,10 +2,16 @@ package storage
 
 import (
 	"fmt"
+	"io"
 	"strconv"
 	"strings"
 )
 
+type DBStream interface {
+	GetStream(string, ...string) (io.Reader, error)
+	SetStream(string, io.Reader, ...string) error
+}
+
 type DB interface {
 	Get(string, ...string) ([]byte, error)
 	Set(string, []byte, ...string) error