diff --git a/0101/kv.go b/0101/kv.go
index 4eefa2a..fbe581d 100644
--- a/0101/kv.go
+++ b/0101/kv.go
@@ -1,5 +1,7 @@
 package db0101
 
+import "bytes"
+
 type KV struct {
 	mem map[string][]byte
 }
@@ -11,10 +13,22 @@ func (kv *KV) Open() error {
 
 func (kv *KV) Close() error { return nil }
 
-func (kv *KV) Get(key []byte) (val []byte, ok bool, err error)
+func (kv *KV) Get(key []byte) (val []byte, ok bool, err error) {
+	val, ok = kv.mem[string(key)]
+	return
+}
 
-func (kv *KV) Set(key []byte, val []byte) (updated bool, err error)
+func (kv *KV) Set(key []byte, val []byte) (updated bool, err error) {
+	prev, exist := kv.mem[string(key)]
+	kv.mem[string(key)] = val
+	updated = !exist || !bytes.Equal(prev, val)
+	return
+}
 
-func (kv *KV) Del(key []byte) (deleted bool, err error)
+func (kv *KV) Del(key []byte) (deleted bool, err error) {
+	_, deleted = kv.mem[string(key)]
+	delete(kv.mem, string(key))
+	return
+}
 
 // QzBQWVJJOUhU https://trialofcode.org/