diff --git a/convertor/convertor.go b/convertor/convertor.go
index 083c4d3..5b995ea 100644
--- a/convertor/convertor.go
+++ b/convertor/convertor.go
@@ -347,7 +347,7 @@ func DeepClone[T any](src T) T {
 func CopyProperties[T, U any](dst T, src U) (err error) {
 	defer func() {
 		if e := recover(); e != nil {
-			err = errors.New(fmt.Sprintf("%v", e))
+			err = fmt.Errorf("%v", e)
 		}
 	}()
 
diff --git a/convertor/convertor_example_test.go b/convertor/convertor_example_test.go
index 8720e48..a1db8e5 100644
--- a/convertor/convertor_example_test.go
+++ b/convertor/convertor_example_test.go
@@ -255,12 +255,12 @@ func ExampleDecodeByte() {
 
 func ExampleDeepClone() {
 	type Struct struct {
-		Str        string
-		Int        int
-		Float      float64
-		Bool       bool
-		Nil        interface{}
-		unexported string
+		Str   string
+		Int   int
+		Float float64
+		Bool  bool
+		Nil   interface{}
+		// unexported string
 	}
 
 	cases := []interface{}{
@@ -293,7 +293,7 @@ func ExampleDeepClone() {
 	// 1 false
 	// 0.1 false
 	// map[a:1 b:2] false
-	// &{test 1 0.1 true <nil> } false
+	// &{test 1 0.1 true <nil>} false
 }
 
 func ExampleCopyProperties() {
@@ -323,12 +323,18 @@ func ExampleCopyProperties() {
 	user := User{Name: "user001", Age: 10, Role: "Admin", Addr: Address{Country: "CN", ZipCode: "001"}, Hobbys: []string{"a", "b"}, salary: 1000}
 
 	employee1 := Employee{}
-	CopyProperties(&employee1, &user)
+	err := CopyProperties(&employee1, &user)
+	if err != nil {
+		return
+	}
 
 	employee2 := Employee{Name: "employee001", Age: 20, Role: "User",
 		Addr: Address{Country: "UK", ZipCode: "002"}, salary: 500}
 
-	CopyProperties(&employee2, &user)
+	err = CopyProperties(&employee2, &user)
+	if err != nil {
+		return
+	}
 
 	fmt.Println(employee1)
 	fmt.Println(employee2)
diff --git a/convertor/convertor_test.go b/convertor/convertor_test.go
index 54bb019..e9fd172 100644
--- a/convertor/convertor_test.go
+++ b/convertor/convertor_test.go
@@ -259,12 +259,12 @@ func TestDeepClone(t *testing.T) {
 	// assert := internal.NewAssert(t, "TestDeepClone")
 
 	type Struct struct {
-		Str        string
-		Int        int
-		Float      float64
-		Bool       bool
-		Nil        interface{}
-		unexported string
+		Str   string
+		Int   int
+		Float float64
+		Bool  bool
+		Nil   interface{}
+		// unexported string
 	}
 
 	cases := []interface{}{
diff --git a/datastructure/hashmap/hashmap.go b/datastructure/hashmap/hashmap.go
index ff257f4..464cb38 100644
--- a/datastructure/hashmap/hashmap.go
+++ b/datastructure/hashmap/hashmap.go
@@ -17,7 +17,7 @@ type mapNode struct {
 	next  *mapNode
 }
 
-//HashMap implements a hash map
+// HashMap implements a hash map
 type HashMap struct {
 	capacity uint64
 	size     uint64
diff --git a/retry/retry_example_test.go b/retry/retry_example_test.go
index ac1d003..3ecb856 100644
--- a/retry/retry_example_test.go
+++ b/retry/retry_example_test.go
@@ -19,11 +19,15 @@ func ExampleContext() {
 		return errors.New("error occurs")
 	}
 
-	Retry(increaseNumber,
+	err := Retry(increaseNumber,
 		RetryDuration(time.Microsecond*50),
 		Context(ctx),
 	)
 
+	if err != nil {
+		return
+	}
+
 	fmt.Println(number)
 
 	// Output:
diff --git a/stream/stream.go b/stream/stream.go
index aa13787..cdab636 100644
--- a/stream/stream.go
+++ b/stream/stream.go
@@ -64,6 +64,7 @@ func Generate[T any](generator func() func() (item T, ok bool)) stream[T] {
 
 	var zeroValue T
 	for next, item, ok := generator(), zeroValue, true; ok; {
+
 		item, ok = next()
 		if ok {
 			source = append(source, item)
@@ -98,7 +99,7 @@ func FromRange[T constraints.Integer | constraints.Float](start, end, step T) st
 	}
 
 	l := int((end-start)/step) + 1
-	source := make([]T, l, l)
+	source := make([]T, l)
 
 	for i := 0; i < l; i++ {
 		source[i] = start + (T(i) * step)
@@ -160,7 +161,7 @@ func (s stream[T]) Filter(predicate func(item T) bool) stream[T] {
 
 // Map returns a stream consisting of the elements of this stream that apply the given function to elements of stream.
 func (s stream[T]) Map(mapper func(item T) T) stream[T] {
-	source := make([]T, s.Count(), s.Count())
+	source := make([]T, s.Count())
 
 	for i, v := range s.source {
 		source[i] = mapper(v)