diff --git a/priority_queuekey/iterator.go b/priority_queuekey/iterator.go
index 95f5473..2174357 100644
--- a/priority_queuekey/iterator.go
+++ b/priority_queuekey/iterator.go
@@ -1,7 +1,7 @@
 package pqueuekey
 
 import (
-	"github.com/474420502/focus/stack/listarraystack"
+	lastack "github.com/474420502/focus/stack/listarraystack"
 )
 
 type Iterator struct {
@@ -50,6 +50,10 @@ func (iter *Iterator) SetNode(n *Node) {
 	iter.tstack.Clear()
 }
 
+func (iter *Iterator) Key() interface{} {
+	return iter.cur.key
+}
+
 func (iter *Iterator) Value() interface{} {
 	return iter.cur.value
 }
diff --git a/tree/avlkey/iterator.go b/tree/avlkey/iterator.go
index 3110331..943fa05 100644
--- a/tree/avlkey/iterator.go
+++ b/tree/avlkey/iterator.go
@@ -1,7 +1,7 @@
 package avlkey
 
 import (
-	"github.com/474420502/focus/stack/listarraystack"
+	lastack "github.com/474420502/focus/stack/listarraystack"
 )
 
 type Iterator struct {
@@ -50,6 +50,10 @@ func (iter *Iterator) SetNode(n *Node) {
 	iter.tstack.Clear()
 }
 
+func (iter *Iterator) Key() interface{} {
+	return iter.cur.key
+}
+
 func (iter *Iterator) Value() interface{} {
 	return iter.cur.value
 }
diff --git a/tree/avlkeydup/iterator.go b/tree/avlkeydup/iterator.go
index a95658e..3c897b0 100644
--- a/tree/avlkeydup/iterator.go
+++ b/tree/avlkeydup/iterator.go
@@ -1,7 +1,7 @@
 package avlkeydup
 
 import (
-	"github.com/474420502/focus/stack/listarraystack"
+	lastack "github.com/474420502/focus/stack/listarraystack"
 )
 
 type Iterator struct {
@@ -50,6 +50,10 @@ func (iter *Iterator) SetNode(n *Node) {
 	iter.tstack.Clear()
 }
 
+func (iter *Iterator) Key() interface{} {
+	return iter.cur.key
+}
+
 func (iter *Iterator) Value() interface{} {
 	return iter.cur.value
 }
diff --git a/tree/vbtkey/iterator.go b/tree/vbtkey/iterator.go
index 8444c5e..556eb4a 100644
--- a/tree/vbtkey/iterator.go
+++ b/tree/vbtkey/iterator.go
@@ -50,6 +50,10 @@ func (iter *Iterator) SetNode(n *Node) {
 	iter.tstack.Clear()
 }
 
+func (iter *Iterator) Key() interface{} {
+	return iter.cur.key
+}
+
 func (iter *Iterator) Value() interface{} {
 	return iter.cur.value
 }