diff --git a/_cmptest/_jsondemo/json.go b/_cmptest/_jsondemo/json.go
new file mode 100644
index 00000000..6f39c82e
--- /dev/null
+++ b/_cmptest/_jsondemo/json.go
@@ -0,0 +1,16 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"unsafe"
+)
+
+func main() {
+	s := `{"name":"math","items":[{"name":"sqrt","sig":"(x, /)"},{"name":"pi"}]}`
+	data := unsafe.Slice(unsafe.StringData(s), len(s))
+	var v any
+	json.Unmarshal(data, &v)
+	b, _ := json.MarshalIndent(v, "", "  ")
+	fmt.Println(string(b))
+}
diff --git a/_cmptest/_timeout/timer.go b/_cmptest/_timeout/timer.go
index bc060890..a830f85e 100644
--- a/_cmptest/_timeout/timer.go
+++ b/_cmptest/_timeout/timer.go
@@ -13,7 +13,7 @@ func main() {
 	select {
 	case m := <-c:
 		handle(m)
-	case <-time.After(10 * time.Second):
+	case <-time.After(time.Second / 10):
 		fmt.Println("timed out")
 	}
 }
diff --git a/_cmptest/printfdemo/demo.go b/_cmptest/printfdemo/demo.go
index 7a20726f..36a2afeb 100644
--- a/_cmptest/printfdemo/demo.go
+++ b/_cmptest/printfdemo/demo.go
@@ -1,19 +1,3 @@
-/*
- * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
 package main
 
 import (