diff --git a/cmd/ledis-cli/main.go b/cmd/ledis-cli/main.go
index 5a3ef89..71ce579 100644
--- a/cmd/ledis-cli/main.go
+++ b/cmd/ledis-cli/main.go
@@ -199,7 +199,7 @@ func loadHisotry() {
 
 func saveHisotry() {
 	if f, err := os.Create(historyPath); err != nil {
-		fmt.Printf("Error writing history file: ", err)
+		fmt.Printf("Error writing history file, err: %v", err)
 	} else {
 		line.WriteHistory(f)
 		f.Close()
diff --git a/ledis/const.go b/ledis/const.go
index d35ca3b..610dada 100644
--- a/ledis/const.go
+++ b/ledis/const.go
@@ -4,8 +4,10 @@ import (
 	"errors"
 )
 
+// Version is for version
 const Version = "0.5"
 
+// DataType is defined for the different types
 type DataType byte
 
 // for out use
@@ -34,6 +36,7 @@ func (d DataType) String() string {
 	}
 }
 
+// For different type name
 const (
 	KVName   = "KV"
 	ListName = "LIST"
@@ -71,24 +74,23 @@ const (
 	MetaType byte = 201
 )
 
-var (
-	TypeName = map[byte]string{
-		KVType:     "kv",
-		HashType:   "hash",
-		HSizeType:  "hsize",
-		ListType:   "list",
-		LMetaType:  "lmeta",
-		ZSetType:   "zset",
-		ZSizeType:  "zsize",
-		ZScoreType: "zscore",
-		// BitType:     "bit",
-		// BitMetaType: "bitmeta",
-		SetType:     "set",
-		SSizeType:   "ssize",
-		ExpTimeType: "exptime",
-		ExpMetaType: "expmeta",
-	}
-)
+// TypeName is the map of type -> name
+var TypeName = map[byte]string{
+	KVType:     "kv",
+	HashType:   "hash",
+	HSizeType:  "hsize",
+	ListType:   "list",
+	LMetaType:  "lmeta",
+	ZSetType:   "zset",
+	ZSizeType:  "zsize",
+	ZScoreType: "zscore",
+	// BitType:     "bit",
+	// BitMetaType: "bitmeta",
+	SetType:     "set",
+	SSizeType:   "ssize",
+	ExpTimeType: "exptime",
+	ExpMetaType: "expmeta",
+}
 
 const (
 	defaultScanCount int = 10
@@ -104,25 +106,28 @@ var (
 	errListIndex      = errors.New("invalid list index")
 )
 
+// For different const size configuration
 const (
+	// max allowed databases
 	MaxDatabases int = 10240
 
-	//max key size
+	// max key size
 	MaxKeySize int = 1024
 
-	//max hash field size
+	// max hash field size
 	MaxHashFieldSize int = 1024
 
-	//max zset member size
+	// max zset member size
 	MaxZSetMemberSize int = 1024
 
-	//max set member size
+	// max set member size
 	MaxSetMemberSize int = 1024
 
-	//max value size
+	// max value size
 	MaxValueSize int = 1024 * 1024 * 1024
 )
 
+// For different common errors
 var (
 	ErrScoreMiss     = errors.New("zset score miss")
 	ErrWriteInROnly  = errors.New("write not support in readonly mode")
@@ -136,6 +141,7 @@ var (
 // 	DBInMulti       uint8 = 0x2
 // )
 
+// For bit operation
 const (
 	BitAND = "and"
 	BitOR  = "or"
diff --git a/ledis/dump.go b/ledis/dump.go
index 3e01ec2..9784575 100644
--- a/ledis/dump.go
+++ b/ledis/dump.go
@@ -11,26 +11,22 @@ import (
 	"github.com/siddontang/ledisdb/store"
 )
 
+// DumpHead is the head of a dump.
 type DumpHead struct {
 	CommitID uint64
 }
 
+// Read reads meta from the Reader.
 func (h *DumpHead) Read(r io.Reader) error {
-	if err := binary.Read(r, binary.BigEndian, &h.CommitID); err != nil {
-		return err
-	}
-
-	return nil
+	return binary.Read(r, binary.BigEndian, &h.CommitID)
 }
 
+// Write writes meta to the Writer
 func (h *DumpHead) Write(w io.Writer) error {
-	if err := binary.Write(w, binary.BigEndian, h.CommitID); err != nil {
-		return err
-	}
-
-	return nil
+	return binary.Write(w, binary.BigEndian, h.CommitID)
 }
 
+// DumpFile dumps data to the file
 func (l *Ledis) DumpFile(path string) error {
 	f, err := os.Create(path)
 	if err != nil {
@@ -41,6 +37,7 @@ func (l *Ledis) DumpFile(path string) error {
 	return l.Dump(f)
 }
 
+// Dump dumps data to the Writer.
 func (l *Ledis) Dump(w io.Writer) error {
 	var err error
 
@@ -118,7 +115,7 @@ func (l *Ledis) Dump(w io.Writer) error {
 	return nil
 }
 
-// clear all data and load dump file to db
+// LoadDumpFile clears all data and loads dump file to db
 func (l *Ledis) LoadDumpFile(path string) (*DumpHead, error) {
 	f, err := os.Open(path)
 	if err != nil {
@@ -129,7 +126,7 @@ func (l *Ledis) LoadDumpFile(path string) (*DumpHead, error) {
 	return l.LoadDump(f)
 }
 
-// clear all data and load dump file to db
+// LoadDump clears all data and loads dump file to db
 func (l *Ledis) LoadDump(r io.Reader) (*DumpHead, error) {
 	l.wLock.Lock()
 	defer l.wLock.Unlock()
diff --git a/ledis/event.go b/ledis/event.go
index d14309d..f35c893 100644
--- a/ledis/event.go
+++ b/ledis/event.go
@@ -29,95 +29,105 @@ func formatEventKey(buf []byte, k []byte) ([]byte, error) {
 
 	switch k[1] {
 	case KVType:
-		if key, err := db.decodeKVKey(k); err != nil {
+		key, err := db.decodeKVKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
 		}
+		buf = strconv.AppendQuote(buf, hack.String(key))
 	case HashType:
-		if key, field, err := db.hDecodeHashKey(k); err != nil {
+		key, field, err := db.hDecodeHashKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
-			buf = append(buf, ' ')
-			buf = strconv.AppendQuote(buf, hack.String(field))
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
+		buf = append(buf, ' ')
+		buf = strconv.AppendQuote(buf, hack.String(field))
 	case HSizeType:
-		if key, err := db.hDecodeSizeKey(k); err != nil {
+		key, err := db.hDecodeSizeKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
 	case ListType:
-		if key, seq, err := db.lDecodeListKey(k); err != nil {
+		key, seq, err := db.lDecodeListKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
-			buf = append(buf, ' ')
-			buf = strconv.AppendInt(buf, int64(seq), 10)
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
+		buf = append(buf, ' ')
+		buf = strconv.AppendInt(buf, int64(seq), 10)
 	case LMetaType:
-		if key, err := db.lDecodeMetaKey(k); err != nil {
+		key, err := db.lDecodeMetaKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
 	case ZSetType:
-		if key, m, err := db.zDecodeSetKey(k); err != nil {
+		key, m, err := db.zDecodeSetKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
-			buf = append(buf, ' ')
-			buf = strconv.AppendQuote(buf, hack.String(m))
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
+		buf = append(buf, ' ')
+		buf = strconv.AppendQuote(buf, hack.String(m))
 	case ZSizeType:
-		if key, err := db.zDecodeSizeKey(k); err != nil {
+		key, err := db.zDecodeSizeKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
 	case ZScoreType:
-		if key, m, score, err := db.zDecodeScoreKey(k); err != nil {
+		key, m, score, err := db.zDecodeScoreKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
-			buf = append(buf, ' ')
-			buf = strconv.AppendQuote(buf, hack.String(m))
-			buf = append(buf, ' ')
-			buf = strconv.AppendInt(buf, score, 10)
 		}
+		buf = strconv.AppendQuote(buf, hack.String(key))
+		buf = append(buf, ' ')
+		buf = strconv.AppendQuote(buf, hack.String(m))
+		buf = append(buf, ' ')
+		buf = strconv.AppendInt(buf, score, 10)
 	case SetType:
-		if key, member, err := db.sDecodeSetKey(k); err != nil {
+		key, member, err := db.sDecodeSetKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
-			buf = append(buf, ' ')
-			buf = strconv.AppendQuote(buf, hack.String(member))
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
+		buf = append(buf, ' ')
+		buf = strconv.AppendQuote(buf, hack.String(member))
 	case SSizeType:
-		if key, err := db.sDecodeSizeKey(k); err != nil {
+		key, err := db.sDecodeSizeKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = strconv.AppendQuote(buf, hack.String(key))
 		}
+
+		buf = strconv.AppendQuote(buf, hack.String(key))
 	case ExpTimeType:
-		if tp, key, t, err := db.expDecodeTimeKey(k); err != nil {
+		tp, key, t, err := db.expDecodeTimeKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = append(buf, TypeName[tp]...)
-			buf = append(buf, ' ')
-			buf = strconv.AppendQuote(buf, hack.String(key))
-			buf = append(buf, ' ')
-			buf = strconv.AppendInt(buf, t, 10)
 		}
+
+		buf = append(buf, TypeName[tp]...)
+		buf = append(buf, ' ')
+		buf = strconv.AppendQuote(buf, hack.String(key))
+		buf = append(buf, ' ')
+		buf = strconv.AppendInt(buf, t, 10)
 	case ExpMetaType:
-		if tp, key, err := db.expDecodeMetaKey(k); err != nil {
+		tp, key, err := db.expDecodeMetaKey(k)
+		if err != nil {
 			return nil, err
-		} else {
-			buf = append(buf, TypeName[tp]...)
-			buf = append(buf, ' ')
-			buf = strconv.AppendQuote(buf, hack.String(key))
 		}
+
+		buf = append(buf, TypeName[tp]...)
+		buf = append(buf, ' ')
+		buf = strconv.AppendQuote(buf, hack.String(key))
 	default:
 		return nil, errInvalidEvent
 	}
diff --git a/ledis/ledis.go b/ledis/ledis.go
index 8d654ba..ab8543c 100644
--- a/ledis/ledis.go
+++ b/ledis/ledis.go
@@ -15,6 +15,7 @@ import (
 	"github.com/siddontang/ledisdb/store"
 )
 
+// Ledis is the core structure to handle the database.
 type Ledis struct {
 	cfg *config.Config
 
@@ -42,6 +43,7 @@ type Ledis struct {
 	ttlCheckerCh chan *ttlChecker
 }
 
+// Open opens the Ledis with a config.
 func Open(cfg *config.Config) (*Ledis, error) {
 	if len(cfg.DataDir) == 0 {
 		cfg.DataDir = config.DefaultDataDir
@@ -96,6 +98,7 @@ func Open(cfg *config.Config) (*Ledis, error) {
 	return l, nil
 }
 
+// Close closes the Ledis.
 func (l *Ledis) Close() {
 	close(l.quit)
 	l.wg.Wait()
@@ -113,6 +116,7 @@ func (l *Ledis) Close() {
 	}
 }
 
+// Select chooses a database.
 func (l *Ledis) Select(index int) (*DB, error) {
 	if index < 0 || index >= l.cfg.Databases {
 		return nil, fmt.Errorf("invalid db index %d, must in [0, %d]", index, l.cfg.Databases-1)
@@ -136,7 +140,7 @@ func (l *Ledis) Select(index int) (*DB, error) {
 	return db, nil
 }
 
-// Flush All will clear all data and replication logs
+// FlushAll will clear all data and replication logs
 func (l *Ledis) FlushAll() error {
 	l.wLock.Lock()
 	defer l.wLock.Unlock()
@@ -181,6 +185,7 @@ func (l *Ledis) flushAll() error {
 	return nil
 }
 
+// IsReadOnly returns whether Ledis is read only or not.
 func (l *Ledis) IsReadOnly() bool {
 	if l.cfg.GetReadonly() {
 		return true
@@ -229,10 +234,12 @@ func (l *Ledis) checkTTL() {
 
 }
 
+// StoreStat returns the statistics.
 func (l *Ledis) StoreStat() *store.Stat {
 	return l.ldb.Stat()
 }
 
+// CompactStore compacts the backend storage.
 func (l *Ledis) CompactStore() error {
 	l.wLock.Lock()
 	defer l.wLock.Unlock()
diff --git a/ledis/ledis_db.go b/ledis/ledis_db.go
index 7b3ff0f..4d250b5 100644
--- a/ledis/ledis_db.go
+++ b/ledis/ledis_db.go
@@ -26,6 +26,7 @@ type ibucket interface {
 	RevRangeLimitIterator(min []byte, max []byte, rangeType uint8, offset int, count int) *store.RangeLimitIterator
 }
 
+// DB is the database.
 type DB struct {
 	l *Ledis
 
@@ -130,6 +131,7 @@ func (db *DB) newBatch() *batch {
 	return db.l.newBatch(db.bucket.NewWriteBatch(), &dbBatchLocker{l: &sync.Mutex{}, wrLock: &db.l.wLock})
 }
 
+// Index gets the index of database.
 func (db *DB) Index() int {
 	return int(db.index)
 }
@@ -138,6 +140,7 @@ func (db *DB) Index() int {
 // 	return db.status == DBAutoCommit
 // }
 
+// FlushAll flushes the data.
 func (db *DB) FlushAll() (drop int64, err error) {
 	all := [...](func() (int64, error)){
 		db.flush,
@@ -147,12 +150,13 @@ func (db *DB) FlushAll() (drop int64, err error) {
 		db.sFlush}
 
 	for _, flush := range all {
-		if n, e := flush(); e != nil {
+		n, e := flush()
+		if e != nil {
 			err = e
 			return
-		} else {
-			drop += n
 		}
+
+		drop += n
 	}
 
 	return
@@ -195,9 +199,9 @@ func (db *DB) flushType(t *batch, dataType byte) (drop int64, err error) {
 
 		if err = t.Commit(); err != nil {
 			return
-		} else {
-			drop += int64(len(keys))
 		}
+
+		drop += int64(len(keys))
 		keys, err = db.scanGeneric(metaDataType, nil, 1024, false, "", false)
 	}
 	return
diff --git a/ledis/migrate.go b/ledis/migrate.go
index aca8a86..eea5b10 100644
--- a/ledis/migrate.go
+++ b/ledis/migrate.go
@@ -14,6 +14,7 @@ import (
    Only support rdb version 6.
 */
 
+// Dump dumps the KV value of key
 func (db *DB) Dump(key []byte) ([]byte, error) {
 	v, err := db.Get(key)
 	if err != nil {
@@ -25,6 +26,7 @@ func (db *DB) Dump(key []byte) ([]byte, error) {
 	return rdb.Dump(rdb.String(v))
 }
 
+// LDump dumps the list value of key
 func (db *DB) LDump(key []byte) ([]byte, error) {
 	v, err := db.LRange(key, 0, -1)
 	if err != nil {
@@ -36,6 +38,7 @@ func (db *DB) LDump(key []byte) ([]byte, error) {
 	return rdb.Dump(rdb.List(v))
 }
 
+// HDump dumps the hash value of key
 func (db *DB) HDump(key []byte) ([]byte, error) {
 	v, err := db.HGetAll(key)
 	if err != nil {
@@ -53,6 +56,7 @@ func (db *DB) HDump(key []byte) ([]byte, error) {
 	return rdb.Dump(o)
 }
 
+// SDump dumps the set value of key
 func (db *DB) SDump(key []byte) ([]byte, error) {
 	v, err := db.SMembers(key)
 	if err != nil {
@@ -64,6 +68,7 @@ func (db *DB) SDump(key []byte) ([]byte, error) {
 	return rdb.Dump(rdb.Set(v))
 }
 
+// ZDump dumps the zset value of key
 func (db *DB) ZDump(key []byte) ([]byte, error) {
 	v, err := db.ZRangeByScore(key, MinScore, MaxScore, 0, -1)
 	if err != nil {
@@ -81,6 +86,7 @@ func (db *DB) ZDump(key []byte) ([]byte, error) {
 	return rdb.Dump(o)
 }
 
+// Restore restores a key into database.
 func (db *DB) Restore(key []byte, ttl int64, data []byte) error {
 	d, err := rdb.DecodeDump(data)
 	if err != nil {
diff --git a/ledis/replication.go b/ledis/replication.go
index 20c2099..b09bdb5 100644
--- a/ledis/replication.go
+++ b/ledis/replication.go
@@ -16,10 +16,12 @@ const (
 	maxReplLogSize = 1 * 1024 * 1024
 )
 
+// For replication error.
 var (
 	ErrLogMissed = errors.New("log is pured in server")
 )
 
+// ReplicationUsed returns whether replication is used or not.
 func (l *Ledis) ReplicationUsed() bool {
 	return l.r != nil
 }
@@ -38,40 +40,39 @@ func (l *Ledis) handleReplication() error {
 			if err != rpl.ErrNoBehindLog {
 				log.Errorf("get next commit log err, %s", err.Error)
 				return err
-			} else {
-				return nil
-			}
-		} else {
-			l.rbatch.Rollback()
-
-			if rl.Compression == 1 {
-				//todo optimize
-				if rl.Data, err = snappy.Decode(nil, rl.Data); err != nil {
-					log.Errorf("decode log error %s", err.Error())
-					return err
-				}
 			}
 
-			if bd, err := store.NewBatchData(rl.Data); err != nil {
-				log.Errorf("decode batch log error %s", err.Error())
-				return err
-			} else if err = bd.Replay(l.rbatch); err != nil {
-				log.Errorf("replay batch log error %s", err.Error())
-			}
+			return nil
+		}
 
-			l.commitLock.Lock()
-			if err = l.rbatch.Commit(); err != nil {
-				log.Errorf("commit log error %s", err.Error())
-			} else if err = l.r.UpdateCommitID(rl.ID); err != nil {
-				log.Errorf("update commit id error %s", err.Error())
-			}
+		l.rbatch.Rollback()
 
-			l.commitLock.Unlock()
-			if err != nil {
+		if rl.Compression == 1 {
+			//todo optimize
+			if rl.Data, err = snappy.Decode(nil, rl.Data); err != nil {
+				log.Errorf("decode log error %s", err.Error())
 				return err
 			}
 		}
 
+		if bd, err := store.NewBatchData(rl.Data); err != nil {
+			log.Errorf("decode batch log error %s", err.Error())
+			return err
+		} else if err = bd.Replay(l.rbatch); err != nil {
+			log.Errorf("replay batch log error %s", err.Error())
+		}
+
+		l.commitLock.Lock()
+		if err = l.rbatch.Commit(); err != nil {
+			log.Errorf("commit log error %s", err.Error())
+		} else if err = l.r.UpdateCommitID(rl.ID); err != nil {
+			log.Errorf("update commit id error %s", err.Error())
+		}
+
+		l.commitLock.Unlock()
+		if err != nil {
+			return err
+		}
 	}
 }
 
@@ -90,6 +91,7 @@ func (l *Ledis) onReplication() {
 	}
 }
 
+// WaitReplication waits replication done
 func (l *Ledis) WaitReplication() error {
 	if !l.ReplicationUsed() {
 		return ErrRplNotSupport
@@ -117,6 +119,7 @@ func (l *Ledis) WaitReplication() error {
 	return errors.New("wait replication too many times")
 }
 
+// StoreLogsFromReader stores logs from the Reader
 func (l *Ledis) StoreLogsFromReader(rb io.Reader) error {
 	if !l.ReplicationUsed() {
 		return ErrRplNotSupport
@@ -150,12 +153,14 @@ func (l *Ledis) noticeReplication() {
 	AsyncNotify(l.rc)
 }
 
+// StoreLogsFromData stores logs from data.
 func (l *Ledis) StoreLogsFromData(data []byte) error {
 	rb := bytes.NewReader(data)
 
 	return l.StoreLogsFromReader(rb)
 }
 
+// ReadLogsTo reads logs and write to the Writer.
 func (l *Ledis) ReadLogsTo(startLogID uint64, w io.Writer) (n int, nextLogID uint64, err error) {
 	if !l.ReplicationUsed() {
 		// no replication log
@@ -205,7 +210,8 @@ func (l *Ledis) ReadLogsTo(startLogID uint64, w io.Writer) (n int, nextLogID uin
 	return
 }
 
-// try to read events, if no events read, try to wait the new event singal until timeout seconds
+// ReadLogsToTimeout tries to read events, if no events read,
+// tres to wait the new event singal until timeout seconds
 func (l *Ledis) ReadLogsToTimeout(startLogID uint64, w io.Writer, timeout int, quitCh chan struct{}) (n int, nextLogID uint64, err error) {
 	n, nextLogID, err = l.ReadLogsTo(startLogID, w)
 	if err != nil {
@@ -229,8 +235,10 @@ func (l *Ledis) propagate(rl *rpl.Log) {
 	}
 }
 
+// NewLogEventHandler is the handler to handle new log event.
 type NewLogEventHandler func(rl *rpl.Log)
 
+// AddNewLogEventHandler adds the handler for the new log event
 func (l *Ledis) AddNewLogEventHandler(h NewLogEventHandler) error {
 	if !l.ReplicationUsed() {
 		return ErrRplNotSupport
@@ -241,6 +249,7 @@ func (l *Ledis) AddNewLogEventHandler(h NewLogEventHandler) error {
 	return nil
 }
 
+// ReplicationStat returns the statistics of repliaciton.
 func (l *Ledis) ReplicationStat() (*rpl.Stat, error) {
 	if !l.ReplicationUsed() {
 		return nil, ErrRplNotSupport
diff --git a/ledis/scan.go b/ledis/scan.go
index c4540a6..b91640f 100644
--- a/ledis/scan.go
+++ b/ledis/scan.go
@@ -10,7 +10,7 @@ import (
 var errDataType = errors.New("error data type")
 var errMetaKey = errors.New("error meta key")
 
-//fif inclusive is true, scan range [cursor, inf) else (cursor, inf)
+//Scan scans the data. If inclusive is true, scan range [cursor, inf) else (cursor, inf)
 func (db *DB) Scan(dataType DataType, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
 	storeDataType, err := getDataStoreType(dataType)
 	if err != nil {
@@ -20,7 +20,7 @@ func (db *DB) Scan(dataType DataType, cursor []byte, count int, inclusive bool,
 	return db.scanGeneric(storeDataType, cursor, count, inclusive, match, false)
 }
 
-//if inclusive is true, revscan range (-inf, cursor] else (inf, cursor)
+// RevScan scans the data reversed. if inclusive is true, revscan range (-inf, cursor] else (inf, cursor)
 func (db *DB) RevScan(dataType DataType, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
 	storeDataType, err := getDataStoreType(dataType)
 	if err != nil {
@@ -51,7 +51,7 @@ func getDataStoreType(dataType DataType) (byte, error) {
 
 func buildMatchRegexp(match string) (*regexp.Regexp, error) {
 	var err error
-	var r *regexp.Regexp = nil
+	var r *regexp.Regexp
 
 	if len(match) > 0 {
 		if r, err = regexp.Compile(match); err != nil {
@@ -300,10 +300,12 @@ func (db *DB) hScanGeneric(key []byte, cursor []byte, count int, inclusive bool,
 	return v, nil
 }
 
+// HScan scans data for hash.
 func (db *DB) HScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]FVPair, error) {
 	return db.hScanGeneric(key, cursor, count, inclusive, match, false)
 }
 
+// HRevScan reversed scans data for hash.
 func (db *DB) HRevScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]FVPair, error) {
 	return db.hScanGeneric(key, cursor, count, inclusive, match, true)
 }
@@ -341,10 +343,12 @@ func (db *DB) sScanGeneric(key []byte, cursor []byte, count int, inclusive bool,
 	return v, nil
 }
 
+// SScan scans data for set.
 func (db *DB) SScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
 	return db.sScanGeneric(key, cursor, count, inclusive, match, false)
 }
 
+// SRevScan scans data reversed for set.
 func (db *DB) SRevScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([][]byte, error) {
 	return db.sScanGeneric(key, cursor, count, inclusive, match, true)
 }
@@ -387,10 +391,12 @@ func (db *DB) zScanGeneric(key []byte, cursor []byte, count int, inclusive bool,
 	return v, nil
 }
 
+// ZScan scans data for zset.
 func (db *DB) ZScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]ScorePair, error) {
 	return db.zScanGeneric(key, cursor, count, inclusive, match, false)
 }
 
+// ZRevScan scans data reversed for zset.
 func (db *DB) ZRevScan(key []byte, cursor []byte, count int, inclusive bool, match string) ([]ScorePair, error) {
 	return db.zScanGeneric(key, cursor, count, inclusive, match, true)
 }
diff --git a/ledis/sort.go b/ledis/sort.go
index 6a54c07..413db10 100644
--- a/ledis/sort.go
+++ b/ledis/sort.go
@@ -9,6 +9,7 @@ import (
 	"github.com/siddontang/ledisdb/store"
 )
 
+// Limit is for sort.
 type Limit struct {
 	Offset int
 	Size   int
@@ -52,7 +53,7 @@ func (db *DB) lookupKeyByPattern(pattern []byte, subKey []byte) []byte {
 	}
 
 	key := pattern
-	var field []byte = nil
+	var field []byte
 
 	// Find out if we're dealing with a hash dereference
 	if n := bytes.Index(pattern, hashPattern); n > 0 && n+3 < len(pattern) {
@@ -109,17 +110,15 @@ func (s *sortItemSlice) Less(i, j int) bool {
 			if s1.cmpValue == nil || s2.cmpValue == nil {
 				if s1.cmpValue == nil {
 					return true
-				} else {
-					return false
 				}
-			} else {
-				// Unlike redis, we only use bytes compare
-				return bytes.Compare(s1.cmpValue, s2.cmpValue) < 0
+				return false
 			}
-		} else {
 			// Unlike redis, we only use bytes compare
-			return bytes.Compare(s1.value, s2.value) < 0
+			return bytes.Compare(s1.cmpValue, s2.cmpValue) < 0
 		}
+
+		// Unlike redis, we only use bytes compare
+		return bytes.Compare(s1.value, s2.value) < 0
 	}
 }
 
@@ -184,7 +183,7 @@ func (db *DB) xsort(values [][]byte, offset int, size int, alpha bool, desc bool
 		}
 	}
 
-	var resLen int = end - start + 1
+	resLen := end - start + 1
 	if len(sortGet) > 0 {
 		resLen = len(sortGet) * (end - start + 1)
 	}
@@ -204,6 +203,7 @@ func (db *DB) xsort(values [][]byte, offset int, size int, alpha bool, desc bool
 	return res, nil
 }
 
+// XLSort sorts list.
 func (db *DB) XLSort(key []byte, offset int, size int, alpha bool, desc bool, sortBy []byte, sortGet [][]byte) ([][]byte, error) {
 	values, err := db.LRange(key, 0, -1)
 
@@ -214,6 +214,7 @@ func (db *DB) XLSort(key []byte, offset int, size int, alpha bool, desc bool, so
 	return db.xsort(values, offset, size, alpha, desc, sortBy, sortGet)
 }
 
+// XSSort sorts set.
 func (db *DB) XSSort(key []byte, offset int, size int, alpha bool, desc bool, sortBy []byte, sortGet [][]byte) ([][]byte, error) {
 	values, err := db.SMembers(key)
 	if err != nil {
@@ -223,6 +224,7 @@ func (db *DB) XSSort(key []byte, offset int, size int, alpha bool, desc bool, so
 	return db.xsort(values, offset, size, alpha, desc, sortBy, sortGet)
 }
 
+// XZSort sorts zset.
 func (db *DB) XZSort(key []byte, offset int, size int, alpha bool, desc bool, sortBy []byte, sortGet [][]byte) ([][]byte, error) {
 	values, err := db.ZRangeByLex(key, nil, nil, store.RangeClose, 0, -1)
 	if err != nil {
diff --git a/ledis/t_hash.go b/ledis/t_hash.go
index c822e23..b9a8595 100644
--- a/ledis/t_hash.go
+++ b/ledis/t_hash.go
@@ -9,6 +9,7 @@ import (
 	"github.com/siddontang/ledisdb/store"
 )
 
+// FVPair is the pair of field and value.
 type FVPair struct {
 	Field []byte
 	Value []byte
@@ -154,7 +155,7 @@ func (db *DB) hDelete(t *batch, key []byte) int64 {
 	start := db.hEncodeStartKey(key)
 	stop := db.hEncodeStopKey(key)
 
-	var num int64 = 0
+	var num int64
 	it := db.bucket.RangeLimitIterator(start, stop, store.RangeROpen, 0, -1)
 	for ; it.Valid(); it.Next() {
 		t.Delete(it.Key())
@@ -173,15 +174,17 @@ func (db *DB) hExpireAt(key []byte, when int64) (int64, error) {
 
 	if hlen, err := db.HLen(key); err != nil || hlen == 0 {
 		return 0, err
-	} else {
-		db.expireAt(t, HashType, key, when)
-		if err := t.Commit(); err != nil {
-			return 0, err
-		}
 	}
+
+	db.expireAt(t, HashType, key, when)
+	if err := t.Commit(); err != nil {
+		return 0, err
+	}
+
 	return 1, nil
 }
 
+// HLen returns the lengh of hash.
 func (db *DB) HLen(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -190,6 +193,7 @@ func (db *DB) HLen(key []byte) (int64, error) {
 	return Int64(db.bucket.Get(db.hEncodeSizeKey(key)))
 }
 
+// HSet sets the field with value of key.
 func (db *DB) HSet(key []byte, field []byte, value []byte) (int64, error) {
 	if err := checkHashKFSize(key, field); err != nil {
 		return 0, err
@@ -210,6 +214,7 @@ func (db *DB) HSet(key []byte, field []byte, value []byte) (int64, error) {
 	return n, err
 }
 
+// HGet gets the value of the field.
 func (db *DB) HGet(key []byte, field []byte) ([]byte, error) {
 	if err := checkHashKFSize(key, field); err != nil {
 		return nil, err
@@ -218,6 +223,7 @@ func (db *DB) HGet(key []byte, field []byte) ([]byte, error) {
 	return db.bucket.Get(db.hEncodeHashKey(key, field))
 }
 
+// HMset sets multi field-values.
 func (db *DB) HMset(key []byte, args ...FVPair) error {
 	t := db.hashBatch
 	t.Lock()
@@ -225,7 +231,7 @@ func (db *DB) HMset(key []byte, args ...FVPair) error {
 
 	var err error
 	var ek []byte
-	var num int64 = 0
+	var num int64
 	for i := 0; i < len(args); i++ {
 		if err := checkHashKFSize(key, args[i].Field); err != nil {
 			return err
@@ -253,6 +259,7 @@ func (db *DB) HMset(key []byte, args ...FVPair) error {
 	return err
 }
 
+// HMget gets multi values of fields
 func (db *DB) HMget(key []byte, args ...[]byte) ([][]byte, error) {
 	var ek []byte
 
@@ -273,6 +280,7 @@ func (db *DB) HMget(key []byte, args ...[]byte) ([][]byte, error) {
 	return r, nil
 }
 
+// HDel deletes the fields.
 func (db *DB) HDel(key []byte, args ...[]byte) (int64, error) {
 	t := db.hashBatch
 
@@ -286,7 +294,7 @@ func (db *DB) HDel(key []byte, args ...[]byte) (int64, error) {
 	it := db.bucket.NewIterator()
 	defer it.Close()
 
-	var num int64 = 0
+	var num int64
 	for i := 0; i < len(args); i++ {
 		if err := checkHashKFSize(key, args[i]); err != nil {
 			return 0, err
@@ -317,23 +325,24 @@ func (db *DB) hIncrSize(key []byte, delta int64) (int64, error) {
 	sk := db.hEncodeSizeKey(key)
 
 	var err error
-	var size int64 = 0
+	var size int64
 	if size, err = Int64(db.bucket.Get(sk)); err != nil {
 		return 0, err
+	}
+
+	size += delta
+	if size <= 0 {
+		size = 0
+		t.Delete(sk)
+		db.rmExpire(t, HashType, key)
 	} else {
-		size += delta
-		if size <= 0 {
-			size = 0
-			t.Delete(sk)
-			db.rmExpire(t, HashType, key)
-		} else {
-			t.Put(sk, PutInt64(size))
-		}
+		t.Put(sk, PutInt64(size))
 	}
 
 	return size, nil
 }
 
+// HIncrBy increases the value of field by delta.
 func (db *DB) HIncrBy(key []byte, field []byte, delta int64) (int64, error) {
 	if err := checkHashKFSize(key, field); err != nil {
 		return 0, err
@@ -348,7 +357,7 @@ func (db *DB) HIncrBy(key []byte, field []byte, delta int64) (int64, error) {
 
 	ek = db.hEncodeHashKey(key, field)
 
-	var n int64 = 0
+	var n int64
 	if n, err = StrInt64(db.bucket.Get(ek)); err != nil {
 		return 0, err
 	}
@@ -365,6 +374,7 @@ func (db *DB) HIncrBy(key []byte, field []byte, delta int64) (int64, error) {
 	return n, err
 }
 
+// HGetAll returns all field-values.
 func (db *DB) HGetAll(key []byte) ([]FVPair, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -390,6 +400,7 @@ func (db *DB) HGetAll(key []byte) ([]FVPair, error) {
 	return v, nil
 }
 
+// HKeys returns the all fields.
 func (db *DB) HKeys(key []byte) ([][]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -414,6 +425,7 @@ func (db *DB) HKeys(key []byte) ([][]byte, error) {
 	return v, nil
 }
 
+// HValues returns all values
 func (db *DB) HValues(key []byte) ([][]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -439,6 +451,7 @@ func (db *DB) HValues(key []byte) ([][]byte, error) {
 	return v, nil
 }
 
+// HClear clears the data.
 func (db *DB) HClear(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -455,6 +468,7 @@ func (db *DB) HClear(key []byte) (int64, error) {
 	return num, err
 }
 
+// HMclear cleans multi data.
 func (db *DB) HMclear(keys ...[]byte) (int64, error) {
 	t := db.hashBatch
 	t.Lock()
@@ -482,6 +496,7 @@ func (db *DB) hFlush() (drop int64, err error) {
 	return db.flushType(t, HashType)
 }
 
+// HExpire expires the data with duration.
 func (db *DB) HExpire(key []byte, duration int64) (int64, error) {
 	if duration <= 0 {
 		return 0, errExpireValue
@@ -490,6 +505,7 @@ func (db *DB) HExpire(key []byte, duration int64) (int64, error) {
 	return db.hExpireAt(key, time.Now().Unix()+duration)
 }
 
+// HExpireAt expires the data at time when.
 func (db *DB) HExpireAt(key []byte, when int64) (int64, error) {
 	if when <= time.Now().Unix() {
 		return 0, errExpireValue
@@ -498,6 +514,7 @@ func (db *DB) HExpireAt(key []byte, when int64) (int64, error) {
 	return db.hExpireAt(key, when)
 }
 
+// HTTL gets the TTL of data.
 func (db *DB) HTTL(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return -1, err
@@ -506,6 +523,7 @@ func (db *DB) HTTL(key []byte) (int64, error) {
 	return db.ttl(HashType, key)
 }
 
+// HPersist removes the TTL of data.
 func (db *DB) HPersist(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -524,6 +542,7 @@ func (db *DB) HPersist(key []byte) (int64, error) {
 	return n, err
 }
 
+// HKeyExists checks whether data exists or not.
 func (db *DB) HKeyExists(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
diff --git a/ledis/t_kv.go b/ledis/t_kv.go
index 624287f..9abec2a 100644
--- a/ledis/t_kv.go
+++ b/ledis/t_kv.go
@@ -11,6 +11,7 @@ import (
 	"github.com/siddontang/ledisdb/store"
 )
 
+// KVPair is the pair of key-value.
 type KVPair struct {
 	Key   []byte
 	Value []byte
@@ -109,23 +110,27 @@ func (db *DB) setExpireAt(key []byte, when int64) (int64, error) {
 
 	if exist, err := db.Exists(key); err != nil || exist == 0 {
 		return 0, err
-	} else {
-		db.expireAt(t, KVType, key, when)
-		if err := t.Commit(); err != nil {
-			return 0, err
-		}
 	}
+
+	db.expireAt(t, KVType, key, when)
+	if err := t.Commit(); err != nil {
+		return 0, err
+	}
+
 	return 1, nil
 }
 
+// Decr decreases the data.
 func (db *DB) Decr(key []byte) (int64, error) {
 	return db.incr(key, -1)
 }
 
+// DecrBy decreases the data by decrement.
 func (db *DB) DecrBy(key []byte, decrement int64) (int64, error) {
 	return db.incr(key, -decrement)
 }
 
+// Del deletes the data.
 func (db *DB) Del(keys ...[]byte) (int64, error) {
 	if len(keys) == 0 {
 		return 0, nil
@@ -149,6 +154,7 @@ func (db *DB) Del(keys ...[]byte) (int64, error) {
 	return int64(len(keys)), err
 }
 
+// Exists check data exists or not.
 func (db *DB) Exists(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -166,6 +172,7 @@ func (db *DB) Exists(key []byte) (int64, error) {
 	return 0, err
 }
 
+// Get gets the value.
 func (db *DB) Get(key []byte) ([]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -176,6 +183,7 @@ func (db *DB) Get(key []byte) ([]byte, error) {
 	return db.bucket.Get(key)
 }
 
+// GetSlice gets the slice of the data.
 func (db *DB) GetSlice(key []byte) (store.Slice, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -186,6 +194,7 @@ func (db *DB) GetSlice(key []byte) (store.Slice, error) {
 	return db.bucket.GetSlice(key)
 }
 
+// GetSet gets the value and sets new value.
 func (db *DB) GetSet(key []byte, value []byte) ([]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -212,14 +221,17 @@ func (db *DB) GetSet(key []byte, value []byte) ([]byte, error) {
 	return oldValue, err
 }
 
+// Incr increases the data.
 func (db *DB) Incr(key []byte) (int64, error) {
 	return db.incr(key, 1)
 }
 
+// IncrBy increases the data by increment.
 func (db *DB) IncrBy(key []byte, increment int64) (int64, error) {
 	return db.incr(key, increment)
 }
 
+// MGet gets multi data.
 func (db *DB) MGet(keys ...[]byte) ([][]byte, error) {
 	values := make([][]byte, len(keys))
 
@@ -237,6 +249,7 @@ func (db *DB) MGet(keys ...[]byte) ([][]byte, error) {
 	return values, nil
 }
 
+// MSet sets multi data.
 func (db *DB) MSet(args ...KVPair) error {
 	if len(args) == 0 {
 		return nil
@@ -270,6 +283,7 @@ func (db *DB) MSet(args ...KVPair) error {
 	return err
 }
 
+// Set sets the data.
 func (db *DB) Set(key []byte, value []byte) error {
 	if err := checkKeySize(key); err != nil {
 		return err
@@ -292,6 +306,7 @@ func (db *DB) Set(key []byte, value []byte) error {
 	return err
 }
 
+// SetNX sets the data if not existed.
 func (db *DB) SetNX(key []byte, value []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -322,6 +337,7 @@ func (db *DB) SetNX(key []byte, value []byte) (int64, error) {
 	return n, err
 }
 
+// SetEX sets the data with a TTL.
 func (db *DB) SetEX(key []byte, duration int64, value []byte) error {
 	if err := checkKeySize(key); err != nil {
 		return err
@@ -341,11 +357,7 @@ func (db *DB) SetEX(key []byte, duration int64, value []byte) error {
 	t.Put(ek, value)
 	db.expireAt(t, KVType, key, time.Now().Unix()+duration)
 
-	if err := t.Commit(); err != nil {
-		return err
-	}
-
-	return nil
+	return t.Commit()
 }
 
 func (db *DB) flush() (drop int64, err error) {
@@ -355,6 +367,7 @@ func (db *DB) flush() (drop int64, err error) {
 	return db.flushType(t, KVType)
 }
 
+// Expire expires the data.
 func (db *DB) Expire(key []byte, duration int64) (int64, error) {
 	if duration <= 0 {
 		return 0, errExpireValue
@@ -363,6 +376,7 @@ func (db *DB) Expire(key []byte, duration int64) (int64, error) {
 	return db.setExpireAt(key, time.Now().Unix()+duration)
 }
 
+// ExpireAt expires the data at when.
 func (db *DB) ExpireAt(key []byte, when int64) (int64, error) {
 	if when <= time.Now().Unix() {
 		return 0, errExpireValue
@@ -371,6 +385,7 @@ func (db *DB) ExpireAt(key []byte, when int64) (int64, error) {
 	return db.setExpireAt(key, when)
 }
 
+// TTL returns the TTL of the data.
 func (db *DB) TTL(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return -1, err
@@ -379,6 +394,7 @@ func (db *DB) TTL(key []byte) (int64, error) {
 	return db.ttl(KVType, key)
 }
 
+// Persist removes the TTL of the data.
 func (db *DB) Persist(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -396,6 +412,7 @@ func (db *DB) Persist(key []byte) (int64, error) {
 	return n, err
 }
 
+// SetRange sets the data with new value from offset.
 func (db *DB) SetRange(key []byte, offset int, value []byte) (int64, error) {
 	if len(value) == 0 {
 		return 0, nil
@@ -458,6 +475,7 @@ func getRange(start int, end int, valLen int) (int, int) {
 	return start, end
 }
 
+// GetRange gets the range of the data.
 func (db *DB) GetRange(key []byte, start int, end int) ([]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -480,6 +498,7 @@ func (db *DB) GetRange(key []byte, start int, end int) ([]byte, error) {
 	return value[start : end+1], nil
 }
 
+// StrLen returns the length of the data.
 func (db *DB) StrLen(key []byte) (int64, error) {
 	s, err := db.GetSlice(key)
 	if err != nil {
@@ -491,6 +510,7 @@ func (db *DB) StrLen(key []byte) (int64, error) {
 	return int64(n), nil
 }
 
+// Append appends the value to the data.
 func (db *DB) Append(key []byte, value []byte) (int64, error) {
 	if len(value) == 0 {
 		return 0, nil
@@ -526,6 +546,7 @@ func (db *DB) Append(key []byte, value []byte) (int64, error) {
 	return int64(len(oldValue)), nil
 }
 
+// BitOP does the bit operations in data.
 func (db *DB) BitOP(op string, destKey []byte, srcKeys ...[]byte) (int64, error) {
 	if err := checkKeySize(destKey); err != nil {
 		return 0, err
@@ -628,6 +649,7 @@ func numberBitCount(i uint32) uint32 {
 	return (((i + (i >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24
 }
 
+// BitCount returns the bit count of data.
 func (db *DB) BitCount(key []byte, start int, end int) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -642,7 +664,7 @@ func (db *DB) BitCount(key []byte, start int, end int) (int64, error) {
 	start, end = getRange(start, end, len(value))
 	value = value[start : end+1]
 
-	var n int64 = 0
+	var n int64
 
 	pos := 0
 	for ; pos+4 <= len(value); pos = pos + 4 {
@@ -656,6 +678,7 @@ func (db *DB) BitCount(key []byte, start int, end int) (int64, error) {
 	return n, nil
 }
 
+// BitPos returns the pos of the data.
 func (db *DB) BitPos(key []byte, on int, start int, end int) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -665,7 +688,7 @@ func (db *DB) BitPos(key []byte, on int, start int, end int) (int64, error) {
 		return 0, fmt.Errorf("bit must be 0 or 1, not %d", on)
 	}
 
-	var skipValue uint8 = 0
+	var skipValue uint8
 	if on == 0 {
 		skipValue = 0xFF
 	}
@@ -694,6 +717,7 @@ func (db *DB) BitPos(key []byte, on int, start int, end int) (int64, error) {
 	return -1, nil
 }
 
+// SetBit sets the bit to the data.
 func (db *DB) SetBit(key []byte, offset int, on int) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -736,11 +760,12 @@ func (db *DB) SetBit(key []byte, offset int, on int) (int64, error) {
 
 	if bitVal > 0 {
 		return 1, nil
-	} else {
-		return 0, nil
 	}
+
+	return 0, nil
 }
 
+// GetBit gets the bit of data at offset.
 func (db *DB) GetBit(key []byte, offset int) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -763,7 +788,7 @@ func (db *DB) GetBit(key []byte, offset int) (int64, error) {
 	bitVal := value[byteOffset] & (1 << bit)
 	if bitVal > 0 {
 		return 1, nil
-	} else {
-		return 0, nil
 	}
+
+	return 0, nil
 }
diff --git a/ledis/t_list.go b/ledis/t_list.go
index 83ed56e..c177cd9 100644
--- a/ledis/t_list.go
+++ b/ledis/t_list.go
@@ -121,12 +121,12 @@ func (db *DB) lpush(key []byte, whereSeq int32, args ...[]byte) (int64, error) {
 		return 0, err
 	}
 
-	var pushCnt int = len(args)
+	pushCnt := len(args)
 	if pushCnt == 0 {
 		return int64(size), nil
 	}
 
-	var seq int32 = headSeq
+	seq := headSeq
 	var delta int32 = -1
 	if whereSeq == listTailSeq {
 		seq = tailSeq
@@ -190,7 +190,7 @@ func (db *DB) lpop(key []byte, whereSeq int32) ([]byte, error) {
 
 	var value []byte
 
-	var seq int32 = headSeq
+	seq := headSeq
 	if whereSeq == listTailSeq {
 		seq = tailSeq
 	}
@@ -202,9 +202,9 @@ func (db *DB) lpop(key []byte, whereSeq int32) ([]byte, error) {
 	}
 
 	if whereSeq == listHeadSeq {
-		headSeq += 1
+		headSeq++
 	} else {
-		tailSeq -= 1
+		tailSeq--
 	}
 
 	t.Delete(itemKey)
@@ -234,25 +234,25 @@ func (db *DB) ltrim2(key []byte, startP, stopP int64) (err error) {
 	ek := db.lEncodeMetaKey(key)
 	if headSeq, _, llen, err = db.lGetMeta(nil, ek); err != nil {
 		return err
-	} else {
-		if start < 0 {
-			start = llen + start
-		}
-		if stop < 0 {
-			stop = llen + stop
-		}
-		if start >= llen || start > stop {
-			db.lDelete(t, key)
-			db.rmExpire(t, ListType, key)
-			return t.Commit()
-		}
+	}
 
-		if start < 0 {
-			start = 0
-		}
-		if stop >= llen {
-			stop = llen - 1
-		}
+	if start < 0 {
+		start = llen + start
+	}
+	if stop < 0 {
+		stop = llen + stop
+	}
+	if start >= llen || start > stop {
+		db.lDelete(t, key)
+		db.rmExpire(t, ListType, key)
+		return t.Commit()
+	}
+
+	if start < 0 {
+		start = 0
+	}
+	if stop >= llen {
+		stop = llen - 1
 	}
 
 	if start > 0 {
@@ -343,11 +343,14 @@ func (db *DB) lDelete(t *batch, key []byte) int64 {
 		return 0
 	}
 
-	var num int64 = 0
+	var num int64
 	startKey := db.lEncodeListKey(key, headSeq)
 	stopKey := db.lEncodeListKey(key, tailSeq)
 
-	rit := store.NewRangeIterator(it, &store.Range{startKey, stopKey, store.RangeClose})
+	rit := store.NewRangeIterator(it, &store.Range{
+		Min:  startKey,
+		Max:  stopKey,
+		Type: store.RangeClose})
 	for ; rit.Valid(); rit.Next() {
 		t.Delete(rit.RawKey())
 		num++
@@ -383,7 +386,7 @@ func (db *DB) lGetMeta(it *store.Iterator, ek []byte) (headSeq int32, tailSeq in
 func (db *DB) lSetMeta(ek []byte, headSeq int32, tailSeq int32) int32 {
 	t := db.listBatch
 
-	var size int32 = tailSeq - headSeq + 1
+	size := tailSeq - headSeq + 1
 	if size < 0 {
 		//	todo : log error + panic
 		log.Fatalf("invalid meta sequence range [%d, %d]", headSeq, tailSeq)
@@ -408,15 +411,17 @@ func (db *DB) lExpireAt(key []byte, when int64) (int64, error) {
 
 	if llen, err := db.LLen(key); err != nil || llen == 0 {
 		return 0, err
-	} else {
-		db.expireAt(t, ListType, key, when)
-		if err := t.Commit(); err != nil {
-			return 0, err
-		}
 	}
+
+	db.expireAt(t, ListType, key, when)
+	if err := t.Commit(); err != nil {
+		return 0, err
+	}
+
 	return 1, nil
 }
 
+// LIndex returns the value at index.
 func (db *DB) LIndex(key []byte, index int32) ([]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -449,6 +454,7 @@ func (db *DB) LIndex(key []byte, index int32) ([]byte, error) {
 	return v, nil
 }
 
+// LLen gets the length of the list.
 func (db *DB) LLen(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -459,25 +465,32 @@ func (db *DB) LLen(key []byte) (int64, error) {
 	return int64(size), err
 }
 
+// LPop pops the value.
 func (db *DB) LPop(key []byte) ([]byte, error) {
 	return db.lpop(key, listHeadSeq)
 }
 
+// LTrim trims the value from start to stop.
 func (db *DB) LTrim(key []byte, start, stop int64) error {
 	return db.ltrim2(key, start, stop)
 }
 
+// LTrimFront trims the value from top.
 func (db *DB) LTrimFront(key []byte, trimSize int32) (int32, error) {
 	return db.ltrim(key, trimSize, listHeadSeq)
 }
 
+// LTrimBack trims the value from back.
 func (db *DB) LTrimBack(key []byte, trimSize int32) (int32, error) {
 	return db.ltrim(key, trimSize, listTailSeq)
 }
 
+// LPush push the value to the list.
 func (db *DB) LPush(key []byte, args ...[]byte) (int64, error) {
 	return db.lpush(key, listHeadSeq, args...)
 }
+
+// LSet sets the value at index.
 func (db *DB) LSet(key []byte, index int32, value []byte) error {
 	if err := checkKeySize(key); err != nil {
 		return err
@@ -512,6 +525,7 @@ func (db *DB) LSet(key []byte, index int32, value []byte) error {
 	return err
 }
 
+// LRange gets the value of list at range.
 func (db *DB) LRange(key []byte, start int32, stop int32) ([][]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -570,14 +584,17 @@ func (db *DB) LRange(key []byte, start int32, stop int32) ([][]byte, error) {
 	return v, nil
 }
 
+// RPop rpops the value.
 func (db *DB) RPop(key []byte) ([]byte, error) {
 	return db.lpop(key, listTailSeq)
 }
 
+// RPush rpushs the value .
 func (db *DB) RPush(key []byte, args ...[]byte) (int64, error) {
 	return db.lpush(key, listTailSeq, args...)
 }
 
+// LClear clears the list.
 func (db *DB) LClear(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -594,6 +611,7 @@ func (db *DB) LClear(key []byte) (int64, error) {
 	return num, err
 }
 
+// LMclear clears multi lists.
 func (db *DB) LMclear(keys ...[]byte) (int64, error) {
 	t := db.listBatch
 	t.Lock()
@@ -620,6 +638,7 @@ func (db *DB) lFlush() (drop int64, err error) {
 	return db.flushType(t, ListType)
 }
 
+// LExpire expires the list.
 func (db *DB) LExpire(key []byte, duration int64) (int64, error) {
 	if duration <= 0 {
 		return 0, errExpireValue
@@ -628,6 +647,7 @@ func (db *DB) LExpire(key []byte, duration int64) (int64, error) {
 	return db.lExpireAt(key, time.Now().Unix()+duration)
 }
 
+// LExpireAt expires the list at when.
 func (db *DB) LExpireAt(key []byte, when int64) (int64, error) {
 	if when <= time.Now().Unix() {
 		return 0, errExpireValue
@@ -636,6 +656,7 @@ func (db *DB) LExpireAt(key []byte, when int64) (int64, error) {
 	return db.lExpireAt(key, when)
 }
 
+// LTTL gets the TTL of list.
 func (db *DB) LTTL(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return -1, err
@@ -644,6 +665,7 @@ func (db *DB) LTTL(key []byte) (int64, error) {
 	return db.ttl(ListType, key)
 }
 
+// LPersist removes the TTL of list.
 func (db *DB) LPersist(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -672,14 +694,17 @@ func (db *DB) lEncodeMaxKey() []byte {
 	return ek
 }
 
+// BLPop pops the list with block way.
 func (db *DB) BLPop(keys [][]byte, timeout time.Duration) ([]interface{}, error) {
 	return db.lblockPop(keys, listHeadSeq, timeout)
 }
 
+// BRPop bpops the list with block way.
 func (db *DB) BRPop(keys [][]byte, timeout time.Duration) ([]interface{}, error) {
 	return db.lblockPop(keys, listTailSeq, timeout)
 }
 
+// LKeyExists check list existed or not.
 func (db *DB) LKeyExists(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
diff --git a/ledis/t_set.go b/ledis/t_set.go
index a4eaf95..926d4ea 100644
--- a/ledis/t_set.go
+++ b/ledis/t_set.go
@@ -12,6 +12,7 @@ import (
 var errSetKey = errors.New("invalid set key")
 var errSSizeKey = errors.New("invalid ssize key")
 
+// For set operation type.
 const (
 	setStartSep byte = ':'
 	setStopSep  byte = setStartSep + 1
@@ -137,7 +138,7 @@ func (db *DB) sDelete(t *batch, key []byte) int64 {
 	start := db.sEncodeStartKey(key)
 	stop := db.sEncodeStopKey(key)
 
-	var num int64 = 0
+	var num int64
 	it := db.bucket.RangeLimitIterator(start, stop, store.RangeROpen, 0, -1)
 	for ; it.Valid(); it.Next() {
 		t.Delete(it.RawKey())
@@ -155,18 +156,18 @@ func (db *DB) sIncrSize(key []byte, delta int64) (int64, error) {
 	sk := db.sEncodeSizeKey(key)
 
 	var err error
-	var size int64 = 0
+	var size int64
 	if size, err = Int64(db.bucket.Get(sk)); err != nil {
 		return 0, err
+	}
+
+	size += delta
+	if size <= 0 {
+		size = 0
+		t.Delete(sk)
+		db.rmExpire(t, SetType, key)
 	} else {
-		size += delta
-		if size <= 0 {
-			size = 0
-			t.Delete(sk)
-			db.rmExpire(t, SetType, key)
-		} else {
-			t.Put(sk, PutInt64(size))
-		}
+		t.Put(sk, PutInt64(size))
 	}
 
 	return size, nil
@@ -179,12 +180,10 @@ func (db *DB) sExpireAt(key []byte, when int64) (int64, error) {
 
 	if scnt, err := db.SCard(key); err != nil || scnt == 0 {
 		return 0, err
-	} else {
-		db.expireAt(t, SetType, key, when)
-		if err := t.Commit(); err != nil {
-			return 0, err
-		}
-
+	}
+	db.expireAt(t, SetType, key, when)
+	if err := t.Commit(); err != nil {
+		return 0, err
 	}
 
 	return 1, nil
@@ -207,6 +206,7 @@ func (db *DB) sSetItem(key []byte, member []byte) (int64, error) {
 	return n, nil
 }
 
+// SAdd adds the value to the set.
 func (db *DB) SAdd(key []byte, args ...[]byte) (int64, error) {
 	t := db.setBatch
 	t.Lock()
@@ -214,7 +214,7 @@ func (db *DB) SAdd(key []byte, args ...[]byte) (int64, error) {
 
 	var err error
 	var ek []byte
-	var num int64 = 0
+	var num int64
 	for i := 0; i < len(args); i++ {
 		if err := checkSetKMSize(key, args[i]); err != nil {
 			return 0, err
@@ -240,6 +240,7 @@ func (db *DB) SAdd(key []byte, args ...[]byte) (int64, error) {
 
 }
 
+// SCard gets the size of set.
 func (db *DB) SCard(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -294,16 +295,19 @@ func (db *DB) sDiffGeneric(keys ...[]byte) ([][]byte, error) {
 	return slice, nil
 }
 
+// SDiff gets the different of sets.
 func (db *DB) SDiff(keys ...[]byte) ([][]byte, error) {
 	v, err := db.sDiffGeneric(keys...)
 	return v, err
 }
 
+// SDiffStore gets the different of sets and stores to dest set.
 func (db *DB) SDiffStore(dstKey []byte, keys ...[]byte) (int64, error) {
 	n, err := db.sStoreGeneric(dstKey, DiffType, keys...)
 	return n, err
 }
 
+// SKeyExists checks whether set existed or not.
 func (db *DB) SKeyExists(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -370,17 +374,20 @@ func (db *DB) sInterGeneric(keys ...[]byte) ([][]byte, error) {
 
 }
 
+// SInter intersects the sets.
 func (db *DB) SInter(keys ...[]byte) ([][]byte, error) {
 	v, err := db.sInterGeneric(keys...)
 	return v, err
 
 }
 
+// SInterStore intersects the sets and stores to dest set.
 func (db *DB) SInterStore(dstKey []byte, keys ...[]byte) (int64, error) {
 	n, err := db.sStoreGeneric(dstKey, InterType, keys...)
 	return n, err
 }
 
+// SIsMember checks member in set.
 func (db *DB) SIsMember(key []byte, member []byte) (int64, error) {
 	ek := db.sEncodeSetKey(key, member)
 
@@ -393,6 +400,7 @@ func (db *DB) SIsMember(key []byte, member []byte) (int64, error) {
 	return n, nil
 }
 
+// SMembers gets members of set.
 func (db *DB) SMembers(key []byte) ([][]byte, error) {
 	if err := checkKeySize(key); err != nil {
 		return nil, err
@@ -418,6 +426,7 @@ func (db *DB) SMembers(key []byte) ([][]byte, error) {
 	return v, nil
 }
 
+// SRem removes the members of set.
 func (db *DB) SRem(key []byte, args ...[]byte) (int64, error) {
 	t := db.setBatch
 	t.Lock()
@@ -430,7 +439,7 @@ func (db *DB) SRem(key []byte, args ...[]byte) (int64, error) {
 	it := db.bucket.NewIterator()
 	defer it.Close()
 
-	var num int64 = 0
+	var num int64
 	for i := 0; i < len(args); i++ {
 		if err := checkSetKMSize(key, args[i]); err != nil {
 			return 0, err
@@ -487,11 +496,13 @@ func (db *DB) sUnionGeneric(keys ...[]byte) ([][]byte, error) {
 	return slice, nil
 }
 
+// SUnion unions the sets.
 func (db *DB) SUnion(keys ...[]byte) ([][]byte, error) {
 	v, err := db.sUnionGeneric(keys...)
 	return v, err
 }
 
+// SUnionStore unions the sets and stores to the dest set.
 func (db *DB) SUnionStore(dstKey []byte, keys ...[]byte) (int64, error) {
 	n, err := db.sStoreGeneric(dstKey, UnionType, keys...)
 	return n, err
@@ -549,6 +560,7 @@ func (db *DB) sStoreGeneric(dstKey []byte, optType byte, keys ...[]byte) (int64,
 	return n, nil
 }
 
+// SClear clears the set.
 func (db *DB) SClear(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -565,6 +577,7 @@ func (db *DB) SClear(key []byte) (int64, error) {
 	return num, err
 }
 
+// SMclear clears multi sets.
 func (db *DB) SMclear(keys ...[]byte) (int64, error) {
 	t := db.setBatch
 	t.Lock()
@@ -583,6 +596,7 @@ func (db *DB) SMclear(keys ...[]byte) (int64, error) {
 	return int64(len(keys)), err
 }
 
+// SExpire expries the set.
 func (db *DB) SExpire(key []byte, duration int64) (int64, error) {
 	if duration <= 0 {
 		return 0, errExpireValue
@@ -592,6 +606,7 @@ func (db *DB) SExpire(key []byte, duration int64) (int64, error) {
 
 }
 
+// SExpireAt expires the set at when.
 func (db *DB) SExpireAt(key []byte, when int64) (int64, error) {
 	if when <= time.Now().Unix() {
 		return 0, errExpireValue
@@ -601,6 +616,7 @@ func (db *DB) SExpireAt(key []byte, when int64) (int64, error) {
 
 }
 
+// STTL gets the TTL of set.
 func (db *DB) STTL(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return -1, err
@@ -609,6 +625,7 @@ func (db *DB) STTL(key []byte) (int64, error) {
 	return db.ttl(SetType, key)
 }
 
+// SPersist removes the TTL of set.
 func (db *DB) SPersist(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
diff --git a/ledis/t_ttl.go b/ledis/t_ttl.go
index 2c979ae..126c8f6 100644
--- a/ledis/t_ttl.go
+++ b/ledis/t_ttl.go
@@ -119,18 +119,22 @@ func (db *DB) ttl(dataType byte, key []byte) (t int64, err error) {
 
 func (db *DB) rmExpire(t *batch, dataType byte, key []byte) (int64, error) {
 	mk := db.expEncodeMetaKey(dataType, key)
-	if v, err := db.bucket.Get(mk); err != nil {
+	v, err := db.bucket.Get(mk)
+	if err != nil {
 		return 0, err
 	} else if v == nil {
 		return 0, nil
-	} else if when, err2 := Int64(v, nil); err2 != nil {
-		return 0, err2
-	} else {
-		tk := db.expEncodeTimeKey(dataType, key, when)
-		t.Delete(mk)
-		t.Delete(tk)
-		return 1, nil
 	}
+
+	when, err2 := Int64(v, nil)
+	if err2 != nil {
+		return 0, err2
+	}
+
+	tk := db.expEncodeTimeKey(dataType, key, when)
+	t.Delete(mk)
+	t.Delete(tk)
+	return 1, nil
 }
 
 func (c *ttlChecker) register(dataType byte, t *batch, f onExpired) {
diff --git a/ledis/t_ttl_test.go b/ledis/t_ttl_test.go
index 1c54a29..dd555ad 100644
--- a/ledis/t_ttl_test.go
+++ b/ledis/t_ttl_test.go
@@ -55,19 +55,19 @@ func listAdaptor(db *DB) *adaptor {
 			eles = append(eles, e)
 		}
 
-		if n, err := db.LPush(k, eles...); err != nil {
+		n, err := db.LPush(k, eles...)
+		if err != nil {
 			return 0, err
-		} else {
-			return n, nil
 		}
+
+		return n, nil
 	}
 
 	adp.exists = func(k []byte) (int64, error) {
 		if llen, err := db.LLen(k); err != nil || llen <= 0 {
 			return 0, err
-		} else {
-			return 1, nil
 		}
+		return 1, nil
 	}
 
 	adp.del = db.LClear
@@ -97,17 +97,15 @@ func hashAdaptor(db *DB) *adaptor {
 
 		if err := db.HMset(k, datas...); err != nil {
 			return 0, err
-		} else {
-			return int64(len(datas)), nil
 		}
+		return int64(len(datas)), nil
 	}
 
 	adp.exists = func(k []byte) (int64, error) {
 		if hlen, err := db.HLen(k); err != nil || hlen <= 0 {
 			return 0, err
-		} else {
-			return 1, nil
 		}
+		return 1, nil
 	}
 
 	adp.del = db.HClear
@@ -135,19 +133,18 @@ func zsetAdaptor(db *DB) *adaptor {
 			datas = append(datas, pair)
 		}
 
-		if n, err := db.ZAdd(k, datas...); err != nil {
+		n, err := db.ZAdd(k, datas...)
+		if err != nil {
 			return 0, err
-		} else {
-			return n, nil
 		}
+		return n, nil
 	}
 
 	adp.exists = func(k []byte) (int64, error) {
 		if cnt, err := db.ZCard(k); err != nil || cnt <= 0 {
 			return 0, err
-		} else {
-			return 1, nil
 		}
+		return 1, nil
 	}
 
 	adp.del = db.ZClear
@@ -171,20 +168,19 @@ func setAdaptor(db *DB) *adaptor {
 			eles = append(eles, e)
 		}
 
-		if n, err := db.SAdd(k, eles...); err != nil {
+		n, err := db.SAdd(k, eles...)
+		if err != nil {
 			return 0, err
-		} else {
-			return n, nil
 		}
-
+		return n, nil
 	}
 
 	adp.exists = func(k []byte) (int64, error) {
 		if slen, err := db.SCard(k); err != nil || slen <= 0 {
 			return 0, err
-		} else {
-			return 1, nil
 		}
+
+		return 1, nil
 	}
 
 	adp.del = db.SClear
diff --git a/ledis/t_zset.go b/ledis/t_zset.go
index fe11df8..030b297 100644
--- a/ledis/t_zset.go
+++ b/ledis/t_zset.go
@@ -10,6 +10,7 @@ import (
 	"github.com/siddontang/ledisdb/store"
 )
 
+// For zset const.
 const (
 	MinScore     int64 = -1<<63 + 1
 	MaxScore     int64 = 1<<63 - 1
@@ -20,6 +21,7 @@ const (
 	AggregateMax byte = 2
 )
 
+// ScorePair is the pair of score and member.
 type ScorePair struct {
 	Score  int64
 	Member []byte
@@ -238,7 +240,7 @@ func (db *DB) zSetItem(t *batch, key []byte, score int64, member []byte) (int64,
 		return 0, errScoreOverflow
 	}
 
-	var exists int64 = 0
+	var exists int64
 	ek := db.zEncodeSetKey(key, member)
 
 	if v, err := db.bucket.Get(ek); err != nil {
@@ -246,12 +248,13 @@ func (db *DB) zSetItem(t *batch, key []byte, score int64, member []byte) (int64,
 	} else if v != nil {
 		exists = 1
 
-		if s, err := Int64(v, err); err != nil {
+		s, err := Int64(v, err)
+		if err != nil {
 			return 0, err
-		} else {
-			sk := db.zEncodeScoreKey(key, member, s)
-			t.Delete(sk)
 		}
+
+		sk := db.zEncodeScoreKey(key, member, s)
+		t.Delete(sk)
 	}
 
 	t.Put(ek, PutInt64(score))
@@ -273,12 +276,12 @@ func (db *DB) zDelItem(t *batch, key []byte, member []byte, skipDelScore bool) (
 		//exists
 		if !skipDelScore {
 			//we must del score
-			if s, err := Int64(v, err); err != nil {
+			s, err := Int64(v, err)
+			if err != nil {
 				return 0, err
-			} else {
-				sk := db.zEncodeScoreKey(key, member, s)
-				t.Delete(sk)
 			}
+			sk := db.zEncodeScoreKey(key, member, s)
+			t.Delete(sk)
 		}
 	}
 
@@ -300,15 +303,17 @@ func (db *DB) zExpireAt(key []byte, when int64) (int64, error) {
 
 	if zcnt, err := db.ZCard(key); err != nil || zcnt == 0 {
 		return 0, err
-	} else {
-		db.expireAt(t, ZSetType, key, when)
-		if err := t.Commit(); err != nil {
-			return 0, err
-		}
 	}
+
+	db.expireAt(t, ZSetType, key, when)
+	if err := t.Commit(); err != nil {
+		return 0, err
+	}
+
 	return 1, nil
 }
 
+// ZAdd add the members.
 func (db *DB) ZAdd(key []byte, args ...ScorePair) (int64, error) {
 	if len(args) == 0 {
 		return 0, nil
@@ -318,7 +323,7 @@ func (db *DB) ZAdd(key []byte, args ...ScorePair) (int64, error) {
 	t.Lock()
 	defer t.Unlock()
 
-	var num int64 = 0
+	var num int64
 	for i := 0; i < len(args); i++ {
 		score := args[i].Score
 		member := args[i].Member
@@ -349,20 +354,20 @@ func (db *DB) zIncrSize(t *batch, key []byte, delta int64) (int64, error) {
 	size, err := Int64(db.bucket.Get(sk))
 	if err != nil {
 		return 0, err
+	}
+	size += delta
+	if size <= 0 {
+		size = 0
+		t.Delete(sk)
+		db.rmExpire(t, ZSetType, key)
 	} else {
-		size += delta
-		if size <= 0 {
-			size = 0
-			t.Delete(sk)
-			db.rmExpire(t, ZSetType, key)
-		} else {
-			t.Put(sk, PutInt64(size))
-		}
+		t.Put(sk, PutInt64(size))
 	}
 
 	return size, nil
 }
 
+// ZCard gets the size of the zset.
 func (db *DB) ZCard(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -372,12 +377,13 @@ func (db *DB) ZCard(key []byte) (int64, error) {
 	return Int64(db.bucket.Get(sk))
 }
 
+// ZScore gets the score of member.
 func (db *DB) ZScore(key []byte, member []byte) (int64, error) {
 	if err := checkZSetKMSize(key, member); err != nil {
 		return InvalidScore, err
 	}
 
-	var score int64 = InvalidScore
+	score := InvalidScore
 
 	k := db.zEncodeSetKey(key, member)
 	if v, err := db.bucket.Get(k); err != nil {
@@ -393,6 +399,7 @@ func (db *DB) ZScore(key []byte, member []byte) (int64, error) {
 	return score, nil
 }
 
+// ZRem removes members
 func (db *DB) ZRem(key []byte, members ...[]byte) (int64, error) {
 	if len(members) == 0 {
 		return 0, nil
@@ -402,7 +409,7 @@ func (db *DB) ZRem(key []byte, members ...[]byte) (int64, error) {
 	t.Lock()
 	defer t.Unlock()
 
-	var num int64 = 0
+	var num int64
 	for i := 0; i < len(members); i++ {
 		if err := checkZSetKMSize(key, members[i]); err != nil {
 			return 0, err
@@ -423,6 +430,7 @@ func (db *DB) ZRem(key []byte, members ...[]byte) (int64, error) {
 	return num, err
 }
 
+// ZIncrBy increases the score of member with delta.
 func (db *DB) ZIncrBy(key []byte, delta int64, member []byte) (int64, error) {
 	if err := checkZSetKMSize(key, member); err != nil {
 		return InvalidScore, err
@@ -434,7 +442,7 @@ func (db *DB) ZIncrBy(key []byte, delta int64, member []byte) (int64, error) {
 
 	ek := db.zEncodeSetKey(key, member)
 
-	var oldScore int64 = 0
+	var oldScore int64
 	v, err := db.bucket.Get(ek)
 	if err != nil {
 		return InvalidScore, err
@@ -465,6 +473,7 @@ func (db *DB) ZIncrBy(key []byte, delta int64, member []byte) (int64, error) {
 	return newScore, err
 }
 
+// ZCount gets the number of score in [min, max]
 func (db *DB) ZCount(key []byte, min int64, max int64) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -475,7 +484,7 @@ func (db *DB) ZCount(key []byte, min int64, max int64) (int64, error) {
 	rangeType := store.RangeROpen
 
 	it := db.bucket.RangeLimitIterator(minKey, maxKey, rangeType, 0, -1)
-	var n int64 = 0
+	var n int64
 	for ; it.Valid(); it.Next() {
 		n++
 	}
@@ -494,39 +503,40 @@ func (db *DB) zrank(key []byte, member []byte, reverse bool) (int64, error) {
 	it := db.bucket.NewIterator()
 	defer it.Close()
 
-	if v := it.Find(k); v == nil {
+	v := it.Find(k)
+	if v == nil {
 		return -1, nil
+	}
+
+	s, err := Int64(v, nil)
+	if err != nil {
+		return 0, err
+	}
+	var rit *store.RangeLimitIterator
+
+	sk := db.zEncodeScoreKey(key, member, s)
+
+	if !reverse {
+		minKey := db.zEncodeStartScoreKey(key, MinScore)
+
+		rit = store.NewRangeIterator(it, &store.Range{Min: minKey, Max: sk, Type: store.RangeClose})
 	} else {
-		if s, err := Int64(v, nil); err != nil {
-			return 0, err
-		} else {
-			var rit *store.RangeLimitIterator
+		maxKey := db.zEncodeStopScoreKey(key, MaxScore)
+		rit = store.NewRevRangeIterator(it, &store.Range{Min: sk, Max: maxKey, Type: store.RangeClose})
+	}
 
-			sk := db.zEncodeScoreKey(key, member, s)
+	var lastKey []byte
+	var n int64
 
-			if !reverse {
-				minKey := db.zEncodeStartScoreKey(key, MinScore)
+	for ; rit.Valid(); rit.Next() {
+		n++
 
-				rit = store.NewRangeIterator(it, &store.Range{minKey, sk, store.RangeClose})
-			} else {
-				maxKey := db.zEncodeStopScoreKey(key, MaxScore)
-				rit = store.NewRevRangeIterator(it, &store.Range{sk, maxKey, store.RangeClose})
-			}
+		lastKey = rit.BufKey(lastKey)
+	}
 
-			var lastKey []byte = nil
-			var n int64 = 0
-
-			for ; rit.Valid(); rit.Next() {
-				n++
-
-				lastKey = rit.BufKey(lastKey)
-			}
-
-			if _, m, _, err := db.zDecodeScoreKey(lastKey); err == nil && bytes.Equal(m, member) {
-				n--
-				return n, nil
-			}
-		}
+	if _, m, _, err := db.zDecodeScoreKey(lastKey); err == nil && bytes.Equal(m, member) {
+		n--
+		return n, nil
 	}
 
 	return -1, nil
@@ -538,9 +548,8 @@ func (db *DB) zIterator(key []byte, min int64, max int64, offset int, count int,
 
 	if !reverse {
 		return db.bucket.RangeLimitIterator(minKey, maxKey, store.RangeClose, offset, count)
-	} else {
-		return db.bucket.RevRangeLimitIterator(minKey, maxKey, store.RangeClose, offset, count)
 	}
+	return db.bucket.RevRangeLimitIterator(minKey, maxKey, store.RangeClose, offset, count)
 }
 
 func (db *DB) zRemRange(t *batch, key []byte, min int64, max int64, offset int, count int) (int64, error) {
@@ -549,7 +558,7 @@ func (db *DB) zRemRange(t *batch, key []byte, min int64, max int64, offset int,
 	}
 
 	it := db.zIterator(key, min, max, offset, count, false)
-	var num int64 = 0
+	var num int64
 	for ; it.Valid(); it.Next() {
 		sk := it.RawKey()
 		_, m, _, err := db.zDecodeScoreKey(sk)
@@ -659,6 +668,7 @@ func (db *DB) zParseLimit(key []byte, start int, stop int) (offset int, count in
 	return
 }
 
+// ZClear clears the zset.
 func (db *DB) ZClear(key []byte) (int64, error) {
 	t := db.zsetBatch
 	t.Lock()
@@ -672,6 +682,7 @@ func (db *DB) ZClear(key []byte) (int64, error) {
 	return rmCnt, err
 }
 
+// ZMclear clears multi zsets.
 func (db *DB) ZMclear(keys ...[]byte) (int64, error) {
 	t := db.zsetBatch
 	t.Lock()
@@ -688,21 +699,25 @@ func (db *DB) ZMclear(keys ...[]byte) (int64, error) {
 	return int64(len(keys)), err
 }
 
+// ZRange gets the members from start to stop.
 func (db *DB) ZRange(key []byte, start int, stop int) ([]ScorePair, error) {
 	return db.ZRangeGeneric(key, start, stop, false)
 }
 
-//min and max must be inclusive
-//if no limit, set offset = 0 and count = -1
+// ZRangeByScore gets the data with score in min and max.
+// min and max must be inclusive
+// if no limit, set offset = 0 and count = -1
 func (db *DB) ZRangeByScore(key []byte, min int64, max int64,
 	offset int, count int) ([]ScorePair, error) {
 	return db.ZRangeByScoreGeneric(key, min, max, offset, count, false)
 }
 
+// ZRank gets the rank of member.
 func (db *DB) ZRank(key []byte, member []byte) (int64, error) {
 	return db.zrank(key, member, false)
 }
 
+// ZRemRangeByRank removes the member at range from start to stop.
 func (db *DB) ZRemRangeByRank(key []byte, start int, stop int) (int64, error) {
 	offset, count, err := db.zParseLimit(key, start, stop)
 	if err != nil {
@@ -723,7 +738,7 @@ func (db *DB) ZRemRangeByRank(key []byte, start int, stop int) (int64, error) {
 	return rmCnt, err
 }
 
-//min and max must be inclusive
+// ZRemRangeByScore removes the data with score at [min, max]
 func (db *DB) ZRemRangeByScore(key []byte, min int64, max int64) (int64, error) {
 	t := db.zsetBatch
 	t.Lock()
@@ -737,20 +752,24 @@ func (db *DB) ZRemRangeByScore(key []byte, min int64, max int64) (int64, error)
 	return rmCnt, err
 }
 
+// ZRevRange gets the data reversed.
 func (db *DB) ZRevRange(key []byte, start int, stop int) ([]ScorePair, error) {
 	return db.ZRangeGeneric(key, start, stop, true)
 }
 
+// ZRevRank gets the rank of member reversed.
 func (db *DB) ZRevRank(key []byte, member []byte) (int64, error) {
 	return db.zrank(key, member, true)
 }
 
-//min and max must be inclusive
-//if no limit, set offset = 0 and count = -1
+// ZRevRangeByScore gets the data with score at [min, max]
+// min and max must be inclusive
+// if no limit, set offset = 0 and count = -1
 func (db *DB) ZRevRangeByScore(key []byte, min int64, max int64, offset int, count int) ([]ScorePair, error) {
 	return db.ZRangeByScoreGeneric(key, min, max, offset, count, true)
 }
 
+// ZRangeGeneric is a generic function for scan zset.
 func (db *DB) ZRangeGeneric(key []byte, start int, stop int, reverse bool) ([]ScorePair, error) {
 	offset, count, err := db.zParseLimit(key, start, stop)
 	if err != nil {
@@ -760,8 +779,9 @@ func (db *DB) ZRangeGeneric(key []byte, start int, stop int, reverse bool) ([]Sc
 	return db.zRange(key, MinScore, MaxScore, offset, count, reverse)
 }
 
-//min and max must be inclusive
-//if no limit, set offset = 0 and count = -1
+// ZRangeByScoreGeneric is a generic function to scan zset with score.
+// min and max must be inclusive
+// if no limit, set offset = 0 and count = -1
 func (db *DB) ZRangeByScoreGeneric(key []byte, min int64, max int64,
 	offset int, count int, reverse bool) ([]ScorePair, error) {
 
@@ -775,6 +795,7 @@ func (db *DB) zFlush() (drop int64, err error) {
 	return db.flushType(t, ZSetType)
 }
 
+// ZExpire expires the zset.
 func (db *DB) ZExpire(key []byte, duration int64) (int64, error) {
 	if duration <= 0 {
 		return 0, errExpireValue
@@ -783,6 +804,7 @@ func (db *DB) ZExpire(key []byte, duration int64) (int64, error) {
 	return db.zExpireAt(key, time.Now().Unix()+duration)
 }
 
+// ZExpireAt expires the zset at when.
 func (db *DB) ZExpireAt(key []byte, when int64) (int64, error) {
 	if when <= time.Now().Unix() {
 		return 0, errExpireValue
@@ -791,6 +813,7 @@ func (db *DB) ZExpireAt(key []byte, when int64) (int64, error) {
 	return db.zExpireAt(key, when)
 }
 
+// ZTTL gets the TTL of zset.
 func (db *DB) ZTTL(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return -1, err
@@ -799,6 +822,7 @@ func (db *DB) ZTTL(key []byte) (int64, error) {
 	return db.ttl(ZSetType, key)
 }
 
+// ZPersist removes the TTL of zset.
 func (db *DB) ZPersist(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
@@ -841,6 +865,7 @@ func getAggregateFunc(aggregate byte) func(int64, int64) int64 {
 	return nil
 }
 
+// ZUnionStore unions the zsets and stores to dest zset.
 func (db *DB) ZUnionStore(destKey []byte, srcKeys [][]byte, weights []int64, aggregate byte) (int64, error) {
 
 	var destMap = map[string]int64{}
@@ -902,6 +927,7 @@ func (db *DB) ZUnionStore(destKey []byte, srcKeys [][]byte, weights []int64, agg
 	return n, nil
 }
 
+// ZInterStore intersects the zsets and stores to dest zset.
 func (db *DB) ZInterStore(destKey []byte, srcKeys [][]byte, weights []int64, aggregate byte) (int64, error) {
 
 	aggregateFunc := getAggregateFunc(aggregate)
@@ -960,7 +986,7 @@ func (db *DB) ZInterStore(destKey []byte, srcKeys [][]byte, weights []int64, agg
 		}
 	}
 
-	var n int64 = int64(len(destMap))
+	n := int64(len(destMap))
 	sk := db.zEncodeSizeKey(destKey)
 	t.Put(sk, PutInt64(n))
 
@@ -970,6 +996,7 @@ func (db *DB) ZInterStore(destKey []byte, srcKeys [][]byte, weights []int64, agg
 	return n, nil
 }
 
+// ZRangeByLex scans the zset lexicographically
 func (db *DB) ZRangeByLex(key []byte, min []byte, max []byte, rangeType uint8, offset int, count int) ([][]byte, error) {
 	if min == nil {
 		min = db.zEncodeStartSetKey(key)
@@ -995,6 +1022,7 @@ func (db *DB) ZRangeByLex(key []byte, min []byte, max []byte, rangeType uint8, o
 	return ay, nil
 }
 
+// ZRemRangeByLex remvoes members in [min, max] lexicographically
 func (db *DB) ZRemRangeByLex(key []byte, min []byte, max []byte, rangeType uint8) (int64, error) {
 	if min == nil {
 		min = db.zEncodeStartSetKey(key)
@@ -1014,7 +1042,7 @@ func (db *DB) ZRemRangeByLex(key []byte, min []byte, max []byte, rangeType uint8
 	it := db.bucket.RangeIterator(min, max, rangeType)
 	defer it.Close()
 
-	var n int64 = 0
+	var n int64
 	for ; it.Valid(); it.Next() {
 		t.Delete(it.RawKey())
 		n++
@@ -1027,6 +1055,7 @@ func (db *DB) ZRemRangeByLex(key []byte, min []byte, max []byte, rangeType uint8
 	return n, nil
 }
 
+// ZLexCount gets the count of zset lexicographically.
 func (db *DB) ZLexCount(key []byte, min []byte, max []byte, rangeType uint8) (int64, error) {
 	if min == nil {
 		min = db.zEncodeStartSetKey(key)
@@ -1042,7 +1071,7 @@ func (db *DB) ZLexCount(key []byte, min []byte, max []byte, rangeType uint8) (in
 	it := db.bucket.RangeIterator(min, max, rangeType)
 	defer it.Close()
 
-	var n int64 = 0
+	var n int64
 	for ; it.Valid(); it.Next() {
 		n++
 	}
@@ -1050,6 +1079,7 @@ func (db *DB) ZLexCount(key []byte, min []byte, max []byte, rangeType uint8) (in
 	return n, nil
 }
 
+// ZKeyExists checks zset existed or not.
 func (db *DB) ZKeyExists(key []byte) (int64, error) {
 	if err := checkKeySize(key); err != nil {
 		return 0, err
diff --git a/ledis/t_zset_test.go b/ledis/t_zset_test.go
index cc0c2b6..b7513a5 100644
--- a/ledis/t_zset_test.go
+++ b/ledis/t_zset_test.go
@@ -155,7 +155,7 @@ func TestZSetOrder(t *testing.T) {
 	} else {
 		for i := 0; i < membCnt; i++ {
 			if string(qMembs[i].Member) != membs[i] {
-				t.Fatal(fmt.Sprintf("[%s] vs [%s]", qMembs[i], membs[i]))
+				t.Fatalf("[%v] vs [%v]", qMembs[i], membs[i])
 			}
 		}
 	}
diff --git a/ledis/util.go b/ledis/util.go
index 26ee6d0..5a054c4 100644
--- a/ledis/util.go
+++ b/ledis/util.go
@@ -15,6 +15,7 @@ var errIntNumber = errors.New("invalid integer")
 	Maybe I was foolish at that time.
 */
 
+// Int64 gets 64 integer with the little endian format.
 func Int64(v []byte, err error) (int64, error) {
 	if err != nil {
 		return 0, err
@@ -27,6 +28,7 @@ func Int64(v []byte, err error) (int64, error) {
 	return int64(binary.LittleEndian.Uint64(v)), nil
 }
 
+// Uint64 gets unsigned 64 integer.
 func Uint64(v []byte, err error) (uint64, error) {
 	if err != nil {
 		return 0, err
@@ -39,12 +41,14 @@ func Uint64(v []byte, err error) (uint64, error) {
 	return binary.LittleEndian.Uint64(v), nil
 }
 
+// PutInt64 puts the 64 integer.
 func PutInt64(v int64) []byte {
 	b := make([]byte, 8)
 	binary.LittleEndian.PutUint64(b, uint64(v))
 	return b
 }
 
+// StrInt64 gets the 64 integer with string format.
 func StrInt64(v []byte, err error) (int64, error) {
 	if err != nil {
 		return 0, err
@@ -55,6 +59,7 @@ func StrInt64(v []byte, err error) (int64, error) {
 	}
 }
 
+// StrUint64 gets the unsigned 64 integer with string format.
 func StrUint64(v []byte, err error) (uint64, error) {
 	if err != nil {
 		return 0, err
@@ -65,6 +70,7 @@ func StrUint64(v []byte, err error) (uint64, error) {
 	}
 }
 
+// StrInt32 gets the 32 integer with string format.
 func StrInt32(v []byte, err error) (int32, error) {
 	if err != nil {
 		return 0, err
@@ -76,6 +82,7 @@ func StrInt32(v []byte, err error) (int32, error) {
 	}
 }
 
+// StrInt8 ets the 8 integer with string format.
 func StrInt8(v []byte, err error) (int8, error) {
 	if err != nil {
 		return 0, err
@@ -87,6 +94,7 @@ func StrInt8(v []byte, err error) (int8, error) {
 	}
 }
 
+// AsyncNotify notices the channel.
 func AsyncNotify(ch chan struct{}) {
 	select {
 	case ch <- struct{}{}:
diff --git a/server/cmd_hash_test.go b/server/cmd_hash_test.go
index f9d19be..17d8317 100644
--- a/server/cmd_hash_test.go
+++ b/server/cmd_hash_test.go
@@ -234,78 +234,78 @@ func TestHashErrorParams(t *testing.T) {
 	defer c.Close()
 
 	if _, err := c.Do("hset", "test_hset"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hget", "test_hget"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hexists", "test_hexists"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hdel", "test_hdel"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hlen", "test_hlen", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hincrby", "test_hincrby"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hmset", "test_hmset"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hmset", "test_hmset", "f1", "v1", "f2"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hmget", "test_hget"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hgetall"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hkeys"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hvals"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hclear", "test_hclear", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hmclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hexpire", "test_hexpire"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hexpireat", "test_hexpireat"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("httl"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("hpersist"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 }
diff --git a/server/cmd_kv_test.go b/server/cmd_kv_test.go
index 6e8cf9d..2db0e1c 100644
--- a/server/cmd_kv_test.go
+++ b/server/cmd_kv_test.go
@@ -248,43 +248,43 @@ func TestKVErrorParams(t *testing.T) {
 	}
 
 	if _, err := c.Do("del"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("mset"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("mset", "a", "b", "c"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("mget"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("expire"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("expire", "a", "b"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("expireat"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("expireat", "a", "b"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("ttl"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("persist"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("setex", "a", "blah", "hello world"); err == nil {
diff --git a/server/cmd_list_test.go b/server/cmd_list_test.go
index 12f0b8a..616b31f 100644
--- a/server/cmd_list_test.go
+++ b/server/cmd_list_test.go
@@ -467,62 +467,62 @@ func TestListErrorParams(t *testing.T) {
 	defer c.Close()
 
 	if _, err := c.Do("lpush", "test_lpush"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("rpush", "test_rpush"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lpop", "test_lpop", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("rpop", "test_rpop", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("llen", "test_llen", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lindex", "test_lindex"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lrange", "test_lrange"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lmclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lexpire"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lexpireat"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lttl"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("lpersist"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("ltrim_front", "test_ltrimfront", "-1"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("ltrim_back", "test_ltrimback", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 }
diff --git a/server/cmd_set_test.go b/server/cmd_set_test.go
index ed9d067..3ad9f8b 100644
--- a/server/cmd_set_test.go
+++ b/server/cmd_set_test.go
@@ -118,99 +118,99 @@ func TestSetErrorParams(t *testing.T) {
 	defer c.Close()
 
 	if _, err := c.Do("sadd", "test_sadd"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("scard"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("scard", "k1", "k2"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sdiff"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sdiffstore", "dstkey"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sinter"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sinterstore", "dstkey"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sunion"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sunionstore", "dstkey"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sismember", "k1"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sismember", "k1", "m1", "m2"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("smembers"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("smembers", "k1", "k2"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("srem"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("srem", "key"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sclear", "k1", "k2"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("smclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sexpire", "set_expire"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sexpire", "set_expire", "aaa"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sexpireat", "set_expireat"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sexpireat", "set_expireat", "aaa"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("sttl"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("spersist"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 }
diff --git a/server/cmd_zset_test.go b/server/cmd_zset_test.go
index b0f4a55..1a673ff 100644
--- a/server/cmd_zset_test.go
+++ b/server/cmd_zset_test.go
@@ -451,166 +451,166 @@ func TestZsetErrorParams(t *testing.T) {
 
 	//zadd
 	if _, err := c.Do("zadd", "test_zadd"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zadd", "test_zadd", "a", "b", "c"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zadd", "test_zadd", "-a", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zadd", "test_zad", "0.1", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zcard
 	if _, err := c.Do("zcard"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zscore
 	if _, err := c.Do("zscore", "test_zscore"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zrem
 	if _, err := c.Do("zrem", "test_zrem"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zincrby
 	if _, err := c.Do("zincrby", "test_zincrby"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zincrby", "test_zincrby", 0.1, "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zcount
 	if _, err := c.Do("zcount", "test_zcount"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zcount", "test_zcount", "-inf", "=inf"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zcount", "test_zcount", 0.1, 0.1); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zrank
 	if _, err := c.Do("zrank", "test_zrank"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zrevzrank
 	if _, err := c.Do("zrevrank", "test_zrevrank"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zremrangebyrank
 	if _, err := c.Do("zremrangebyrank", "test_zremrangebyrank"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zremrangebyrank", "test_zremrangebyrank", 0.1, 0.1); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zremrangebyscore
 	if _, err := c.Do("zremrangebyscore", "test_zremrangebyscore"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zremrangebyscore", "test_zremrangebyscore", "-inf", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zremrangebyscore", "test_zremrangebyscore", 0, "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zrange
 	if _, err := c.Do("zrange", "test_zrange"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zrange", "test_zrange", 0, 1, "withscore"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zrange", "test_zrange", 0, 1, "withscores", "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zrevrange, almost same as zrange
 	if _, err := c.Do("zrevrange", "test_zrevrange"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zrangebyscore
 	if _, err := c.Do("zrangebyscore", "test_zrangebyscore"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zrangebyscore", "test_zrangebyscore", 0, 1, "withscore"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zrangebyscore", "test_zrangebyscore", 0, 1, "withscores", "limit"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zrangebyscore", "test_zrangebyscore", 0, 1, "withscores", "limi", 1, 1); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zrangebyscore", "test_zrangebyscore", 0, 1, "withscores", "limit", "a", 1); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	if _, err := c.Do("zrangebyscore", "test_zrangebyscore", 0, 1, "withscores", "limit", 1, "a"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zrevrangebyscore, almost same as zrangebyscore
 	if _, err := c.Do("zrevrangebyscore", "test_zrevrangebyscore"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zclear
 	if _, err := c.Do("zclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zmclear
 	if _, err := c.Do("zmclear"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zexpire
 	if _, err := c.Do("zexpire", "test_zexpire"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zexpireat
 	if _, err := c.Do("zexpireat", "test_zexpireat"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zttl
 	if _, err := c.Do("zttl"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 	//zpersist
 	if _, err := c.Do("zpersist"); err == nil {
-		t.Fatal("invalid err of %v", err)
+		t.Fatalf("invalid err of %v", err)
 	}
 
 }