diff --git a/iterator.go b/iterator.go
index ba0d7ae..35aeade 100644
--- a/iterator.go
+++ b/iterator.go
@@ -79,23 +79,3 @@ func (t *Rbtree) ascendRange(x *Node, inf, sup Item, iterator Iterator) bool {
 	}
 	return t.ascendRange(x.Right, inf, sup, iterator)
 }
-
-func (t *Rbtree) Min() Item {
-	x := t.min(t.root)
-
-	if x == t.NIL {
-		return nil
-	}
-
-	return x.Item
-}
-
-func (t *Rbtree) Max() Item {
-	x := t.max(t.root)
-
-	if x == t.NIL {
-		return nil
-	}
-
-	return x.Item
-}
diff --git a/rbtree.go b/rbtree.go
index 57cc1d4..678e985 100644
--- a/rbtree.go
+++ b/rbtree.go
@@ -48,8 +48,6 @@ func less(x, y Item) bool {
 // New returns an initialized Red-Black tree
 func New() *Rbtree { return new(Rbtree).Init() }
 
-func (t *Rbtree) Len() uint { return t.count }
-
 func (t *Rbtree) Init() *Rbtree {
 	node := &Node{nil, nil, nil, BLACK, nil}
 	return &Rbtree{
@@ -135,41 +133,6 @@ func (t *Rbtree) rightRotate(x *Node) {
 	x.Parent = y
 }
 
-// Use by client
-func (t *Rbtree) Insert(item Item) {
-	if item == nil {
-		return
-	}
-
-	// Always insert a RED node
-	t.insert(&Node{t.NIL, t.NIL, t.NIL, RED, item})
-}
-
-// Use by client
-func (t *Rbtree) Delete(item Item) {
-	if item == nil {
-		return
-	}
-
-	// The `color` field here is nobody
-	t.delete(&Node{t.NIL, t.NIL, t.NIL, RED, item})
-}
-
-// Use by client
-func (t *Rbtree) Get(item Item) Item {
-	if item == nil {
-		return nil
-	}
-
-	// The `color` field here is nobody
-	ret := t.search(&Node{t.NIL, t.NIL, t.NIL, RED, item})
-	if ret == nil {
-		return nil
-	}
-
-	return ret.Item
-}
-
 func (t *Rbtree) insert(z *Node) {
 	x := t.root
 	y := t.NIL
@@ -313,12 +276,6 @@ func (t *Rbtree) max(x *Node) *Node {
 	return x
 }
 
-//TODO: This is for debug, delete it in the future
-func (t *Rbtree) Search(item Item) *Node {
-
-	return t.search(&Node{t.NIL, t.NIL, t.NIL, RED, item})
-}
-
 func (t *Rbtree) search(x *Node) *Node {
 	p := t.root
 
diff --git a/stats.go b/stats.go
new file mode 100644
index 0000000..8b2b36a
--- /dev/null
+++ b/stats.go
@@ -0,0 +1,70 @@
+// Copyright 2015, Hu Keping . All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package rbtree
+
+// This file contains most of the methods that can be used
+// by the user. Anyone who wants to look for some API about
+// the rbtree, this is the right place.
+
+// Number of nodes in the tree.
+func (t *Rbtree) Len() uint { return t.count }
+
+func (t *Rbtree) Insert(item Item) {
+	if item == nil {
+		return
+	}
+
+	// Always insert a RED node
+	t.insert(&Node{t.NIL, t.NIL, t.NIL, RED, item})
+}
+
+func (t *Rbtree) Delete(item Item) {
+	if item == nil {
+		return
+	}
+
+	// The `color` field here is nobody
+	t.delete(&Node{t.NIL, t.NIL, t.NIL, RED, item})
+}
+
+func (t *Rbtree) Get(item Item) Item {
+	if item == nil {
+		return nil
+	}
+
+	// The `color` field here is nobody
+	ret := t.search(&Node{t.NIL, t.NIL, t.NIL, RED, item})
+	if ret == nil {
+		return nil
+	}
+
+	return ret.Item
+}
+
+//TODO: This is for debug, delete it in the future
+func (t *Rbtree) Search(item Item) *Node {
+
+	return t.search(&Node{t.NIL, t.NIL, t.NIL, RED, item})
+}
+
+func (t *Rbtree) Min() Item {
+	x := t.min(t.root)
+
+	if x == t.NIL {
+		return nil
+	}
+
+	return x.Item
+}
+
+func (t *Rbtree) Max() Item {
+	x := t.max(t.root)
+
+	if x == t.NIL {
+		return nil
+	}
+
+	return x.Item
+}