diff --git a/src/shardkv1/shardctrler/shardctrler.go b/src/shardkv1/shardctrler/shardctrler.go
index f260c19..07a80f0 100644
--- a/src/shardkv1/shardctrler/shardctrler.go
+++ b/src/shardkv1/shardctrler/shardctrler.go
@@ -52,7 +52,7 @@ func (sck *ShardCtrler) InitConfig(cfg *shardcfg.ShardConfig) {
 // changes the configuration it may be superseded by another
 // controller.
 func (sck *ShardCtrler) ChangeConfigTo(new *shardcfg.ShardConfig) {
-	return
+	// Your code here.
 }
 
 
diff --git a/src/shardkv1/shardgrp/client.go b/src/shardkv1/shardgrp/client.go
index ed2b209..29c71e2 100644
--- a/src/shardkv1/shardgrp/client.go
+++ b/src/shardkv1/shardgrp/client.go
@@ -30,13 +30,16 @@ func (ck *Clerk) Put(key string, value string, version rpc.Tversion) rpc.Err {
 }
 
 func (ck *Clerk) FreezeShard(s shardcfg.Tshid, num shardcfg.Tnum) ([]byte, rpc.Err) {
+	// Your code here
 	return nil, ""
 }
 
 func (ck *Clerk) InstallShard(s shardcfg.Tshid, state []byte, num shardcfg.Tnum) rpc.Err {
+	// Your code here
 	return ""
 }
 
 func (ck *Clerk) DeleteShard(s shardcfg.Tshid, num shardcfg.Tnum) rpc.Err {
+	// Your code here
 	return ""
 }