diff --git a/README.md b/README.md
index 4fd39a4..8894bc8 100644
--- a/README.md
+++ b/README.md
@@ -162,7 +162,7 @@ import "github.com/duke-git/lancet/v2/condition"
     [[play](https://go.dev/play/p/W1SSUmt6pvr)]
 -   **<big>Or</big>** : returns false if neither a nor b is truthy.
     [[doc](https://github.com/duke-git/lancet/blob/main/docs/condition.md#Or)]
-    [[play](https://go.dev/play/p/UlQTxHaeEkq)]
+    [[play](https://go.dev/play/p/UlQTxHaeEkq)]]
 -   **<big>Xor</big>** : returns true if a or b but not both is truthy.
     [[doc](https://github.com/duke-git/lancet/blob/main/docs/condition.md#Xor)]
     [[play](https://go.dev/play/p/gObZrW7ZbG8)]
diff --git a/README_zh-CN.md b/README_zh-CN.md
index 91d9a21..62b3eae 100644
--- a/README_zh-CN.md
+++ b/README_zh-CN.md
@@ -170,7 +170,7 @@ import "github.com/duke-git/lancet/v2/condition"
     [[play](https://go.dev/play/p/g2j08F_zZky)
 -   **<big>Xnor</big>** : 如果 a 和 b 都是真的或 a 和 b 均是假的，则返回 true。
     [[doc](https://github.com/duke-git/lancet/blob/main/docs/condition_zh-CN.md#Xnor)]
-    [[play](https://go.dev/play/p/OuDB9g51643)]
+    [[play](https://go.dev/play/p/OuDB9g51643)]]
 -   **<big>Nand</big>** : 如果 a 和 b 都为真，返回 false，否则返回 true
     [[doc](https://github.com/duke-git/lancet/blob/main/docs/condition_zh-CN.md#Nand)]
     [[play](https://go.dev/play/p/vSRMLxLIbq8)]
diff --git a/algorithm/search.go b/algorithm/search.go
index b44b1a6..0d85cad 100644
--- a/algorithm/search.go
+++ b/algorithm/search.go
@@ -10,6 +10,7 @@ import "github.com/duke-git/lancet/v2/lancetconstraints"
 
 // LinearSearch return the index of target in slice base on equal function.
 // If not found return -1
+// Play: Todo
 func LinearSearch[T any](slice []T, target T, equal func(a, b T) bool) int {
 	for i, v := range slice {
 		if equal(v, target) {
diff --git a/concurrency/channel.go b/concurrency/channel.go
index c235018..8629e87 100644
--- a/concurrency/channel.go
+++ b/concurrency/channel.go
@@ -20,7 +20,7 @@ func NewChannel[T any]() *Channel[T] {
 }
 
 // Generate creates channel, then put values into the channel.
-// Play:
+// Play: Todo
 func (c *Channel[T]) Generate(ctx context.Context, values ...T) <-chan T {
 	dataStream := make(chan T)
 
@@ -40,7 +40,7 @@ func (c *Channel[T]) Generate(ctx context.Context, values ...T) <-chan T {
 }
 
 // Repeat create channel, put values into the channel repeatly until cancel the context.
-// Play:
+// Play: Todo
 func (c *Channel[T]) Repeat(ctx context.Context, values ...T) <-chan T {
 	dataStream := make(chan T)
 
@@ -61,7 +61,7 @@ func (c *Channel[T]) Repeat(ctx context.Context, values ...T) <-chan T {
 
 // RepeatFn create a channel, excutes fn repeatly, and put the result into the channel
 // until close context.
-// Play:
+// Play: Todo
 func (c *Channel[T]) RepeatFn(ctx context.Context, fn func() T) <-chan T {
 	dataStream := make(chan T)
 
@@ -79,7 +79,7 @@ func (c *Channel[T]) RepeatFn(ctx context.Context, fn func() T) <-chan T {
 }
 
 // Take create a channel whose values are taken from another channel with limit number.
-// Play:
+// Play: Todo
 func (c *Channel[T]) Take(ctx context.Context, valueStream <-chan T, number int) <-chan T {
 	takeStream := make(chan T)
 
@@ -99,7 +99,7 @@ func (c *Channel[T]) Take(ctx context.Context, valueStream <-chan T, number int)
 }
 
 // FanIn merge multiple channels into one channel.
-// Play:
+// Play: Todo
 func (c *Channel[T]) FanIn(ctx context.Context, channels ...<-chan T) <-chan T {
 	out := make(chan T)
 
@@ -127,7 +127,7 @@ func (c *Channel[T]) FanIn(ctx context.Context, channels ...<-chan T) <-chan T {
 }
 
 // Tee split one chanel into two channels, until cancel the context.
-// Play:
+// Play: Todo
 func (c *Channel[T]) Tee(ctx context.Context, in <-chan T) (<-chan T, <-chan T) {
 	out1 := make(chan T)
 	out2 := make(chan T)
@@ -154,7 +154,7 @@ func (c *Channel[T]) Tee(ctx context.Context, in <-chan T) (<-chan T, <-chan T)
 }
 
 // Bridge link multiply channels into one channel.
-// Play:
+// Play: Todo
 func (c *Channel[T]) Bridge(ctx context.Context, chanStream <-chan <-chan T) <-chan T {
 	valStream := make(chan T)
 
@@ -186,7 +186,7 @@ func (c *Channel[T]) Bridge(ctx context.Context, chanStream <-chan <-chan T) <-c
 }
 
 // Or read one or more channels into one channel, will close when any readin channel is closed.
-// Play:
+// Play: Todo
 func (c *Channel[T]) Or(channels ...<-chan T) <-chan T {
 	switch len(channels) {
 	case 0:
@@ -220,7 +220,7 @@ func (c *Channel[T]) Or(channels ...<-chan T) <-chan T {
 }
 
 // OrDone read a channel into another channel, will close until cancel context.
-// Play:
+// Play: Todo
 func (c *Channel[T]) OrDone(ctx context.Context, channel <-chan T) <-chan T {
 	valStream := make(chan T)
 
diff --git a/mathutil/mathutil.go b/mathutil/mathutil.go
index 0a8ffe2..4ce167e 100644
--- a/mathutil/mathutil.go
+++ b/mathutil/mathutil.go
@@ -55,6 +55,7 @@ func Factorial(x uint) uint {
 }
 
 // Percent calculate the percentage of value to total.
+// Play: Todo
 func Percent(val, total float64, n int) float64 {
 	if total == 0 {
 		return float64(0)
diff --git a/strutil/string.go b/strutil/string.go
index 8dd0ba2..1dcc45d 100644
--- a/strutil/string.go
+++ b/strutil/string.go
@@ -283,6 +283,7 @@ func SplitEx(s, sep string, removeEmptyString bool) []string {
 }
 
 // Substring returns a substring of the specified length starting at the specified offset position.
+// Play: Todo
 func Substring(s string, offset int, length uint) string {
 	rs := []rune(s)
 	size := len(rs)