diff --git a/observable/iterable.go b/observable/iterable.go
index 78929945..ad0943b5 100644
--- a/observable/iterable.go
+++ b/observable/iterable.go
@@ -1,18 +1,3 @@
 package observable
 
-import (
-	"errors"
-)
-
 type Iterable <-chan interface{}
-
-func NewIterable(any interface{}) (Iterable, error) {
-	switch any := any.(type) {
-	case chan interface{}:
-		return Iterable(any), nil
-	case <-chan interface{}:
-		return Iterable(any), nil
-	default:
-		return nil, errors.New("type error")
-	}
-}
diff --git a/observable/observable.go b/observable/observable.go
index 5ba292ec..4b216d4f 100644
--- a/observable/observable.go
+++ b/observable/observable.go
@@ -50,7 +50,6 @@ func (o *Observable) Subscribe() (Subscription, error) {
 func (o *Observable) UnSubscribe(sub Subscription) {
 	elm, exist := o.listener.Load(sub)
 	if !exist {
-		println("not exist")
 		return
 	}
 	subscriber := elm.(*Subscriber)
diff --git a/observable/observable_test.go b/observable/observable_test.go
index 10bef10d..c3d178db 100644
--- a/observable/observable_test.go
+++ b/observable/observable_test.go
@@ -27,11 +27,7 @@ func TestObservable(t *testing.T) {
 		t.Error(err)
 	}
 	count := 0
-	for {
-		_, open := <-data
-		if !open {
-			break
-		}
+	for range data {
 		count = count + 1
 	}
 	if count != 5 {
@@ -49,11 +45,7 @@ func TestObservable_MutilSubscribe(t *testing.T) {
 	var wg sync.WaitGroup
 	wg.Add(2)
 	waitCh := func(ch <-chan interface{}) {
-		for {
-			_, open := <-ch
-			if !open {
-				break
-			}
+		for range ch {
 			count = count + 1
 		}
 		wg.Done()
@@ -80,6 +72,25 @@ func TestObservable_UnSubscribe(t *testing.T) {
 	}
 }
 
+func TestObservable_SubscribeClosedSource(t *testing.T) {
+	iter := iterator([]interface{}{1})
+	src := NewObservable(iter)
+	data, _ := src.Subscribe()
+	<-data
+
+	_, closed := src.Subscribe()
+	if closed == nil {
+		t.Error("Observable should be closed")
+	}
+}
+
+func TestObservable_UnSubscribeWithNotExistSubscription(t *testing.T) {
+	sub := Subscription(make(chan interface{}))
+	iter := iterator([]interface{}{1})
+	src := NewObservable(iter)
+	src.UnSubscribe(sub)
+}
+
 func TestObservable_SubscribeGoroutineLeak(t *testing.T) {
 	// waiting for other goroutine recycle
 	time.Sleep(120 * time.Millisecond)
@@ -97,11 +108,7 @@ func TestObservable_SubscribeGoroutineLeak(t *testing.T) {
 	var wg sync.WaitGroup
 	wg.Add(max)
 	waitCh := func(ch <-chan interface{}) {
-		for {
-			_, open := <-ch
-			if !open {
-				break
-			}
+		for range ch {
 		}
 		wg.Done()
 	}
diff --git a/observable/util.go b/observable/util.go
deleted file mode 100644
index d7d02b0b..00000000
--- a/observable/util.go
+++ /dev/null
@@ -1,15 +0,0 @@
-package observable
-
-func mergeWithBytes(ch <-chan interface{}, buf []byte) chan interface{} {
-	out := make(chan interface{})
-	go func() {
-		defer close(out)
-		if len(buf) != 0 {
-			out <- buf
-		}
-		for elm := range ch {
-			out <- elm
-		}
-	}()
-	return out
-}