diff --git a/README.md b/README.md
index deb7f2f..1d56bbc 100644
--- a/README.md
+++ b/README.md
@@ -207,6 +207,7 @@ And add more detailed documents.
 ## Go Doc
 
 Clock to view the [generated doc](generated_doc.md).
+
 ## Reference
 
 - [C++ STL](https://en.wikipedia.org/wiki/Standard_Template_Library)
diff --git a/builtin_set.go b/builtin_set.go
index b0f70ec..68d285c 100644
--- a/builtin_set.go
+++ b/builtin_set.go
@@ -14,47 +14,56 @@ func MakeBuiltinSetOf[K comparable](ks ...K) BuiltinSet[K] {
 	return s
 }
 
+// IsEmpty implements the Container interface.
 func (s *BuiltinSet[K]) IsEmpty() bool {
 	return len(*s) == 0
 }
 
+// Len implements the Container interface.
 func (s *BuiltinSet[K]) Len() int {
 	return len(*s)
 }
 
+// Clear implements the Container interface.
 func (s *BuiltinSet[K]) Clear() {
 	for k := range *s {
 		delete(*s, k)
 	}
 }
 
+// Has implements the Set interface.
 func (s *BuiltinSet[K]) Has(k K) bool {
 	_, ok := (*s)[k]
 	return ok
 }
 
+// Insert implements the Set interface.
 func (s *BuiltinSet[K]) Insert(k K) {
 	(*s)[k] = true
 }
 
+// InsertN implements the Set interface.
 func (s *BuiltinSet[K]) InsertN(ks ...K) {
 	for _, key := range ks {
 		(*s)[key] = true
 	}
 }
 
+// Remove implements the Set interface.
 func (s *BuiltinSet[K]) Remove(k K) bool {
 	_, ok := (*s)[k]
 	delete(*s, k)
 	return ok
 }
 
+// RemoveN implements the Set interface.
 func (s *BuiltinSet[K]) RemoveN(ks ...K) {
 	for _, k := range ks {
 		delete(*s, k)
 	}
 }
 
+// Keys return a copy of all keys as a slice.
 func (s *BuiltinSet[K]) Keys() []K {
 	keys := make([]K, 0, len(*s))
 	for k := range *s {
@@ -63,12 +72,14 @@ func (s *BuiltinSet[K]) Keys() []K {
 	return keys
 }
 
+// ForEach implements the Set interface.
 func (s *BuiltinSet[K]) ForEach(cb func(k K)) {
 	for k := range *s {
 		cb(k)
 	}
 }
 
+// ForEachIf implements the Container interface.
 func (s *BuiltinSet[K]) ForEachIf(cb func(k K) bool) {
 	for k := range *s {
 		if !cb(k) {
@@ -77,6 +88,7 @@ func (s *BuiltinSet[K]) ForEachIf(cb func(k K) bool) {
 	}
 }
 
+// String implements the fmt.Stringer interface
 func (s BuiltinSet[K]) String() string {
 	return fmt.Sprintf("BuiltinSet[%s]%v", nameOfType[K](), s.Keys())
 }
diff --git a/dlist.go b/dlist.go
index a65478e..e624c8b 100644
--- a/dlist.go
+++ b/dlist.go
@@ -74,6 +74,7 @@ func (l *DList[T]) Iterate() Iterator[T] {
 	return &dlistIterator[T]{l, l.head.next}
 }
 
+// PushFront pushes an element at the front of the list.
 func (l *DList[T]) PushFront(val T) {
 	n := dListNode[T]{&l.head, l.head.next, val}
 	l.head.next.prev = &n
@@ -81,6 +82,7 @@ func (l *DList[T]) PushFront(val T) {
 	l.length++
 }
 
+// PushBack pushes an element at the back of the list.
 func (l *DList[T]) PushBack(val T) {
 	n := dListNode[T]{l.head.prev, &l.head, val}
 	l.head.prev.next = &n
@@ -88,6 +90,7 @@ func (l *DList[T]) PushBack(val T) {
 	l.length++
 }
 
+// PopFront popups a element from the front of the list.
 func (l *DList[T]) PopFront() (T, bool) {
 	var val T
 	if l.length == 0 {
@@ -100,6 +103,7 @@ func (l *DList[T]) PopFront() (T, bool) {
 	return val, true
 }
 
+// PopBack popups a element from the back of the list.
 func (l *DList[T]) PopBack() (T, bool) {
 	var val T
 	if l.length == 0 {
@@ -119,7 +123,7 @@ func (l *DList[T]) ForEach(cb func(val T)) {
 	}
 }
 
-// ForEach iterate the list, apply each element to the cb callback function, stop if cb returns false.
+// ForEachIf iterate the list, apply each element to the cb callback function, stop if cb returns false.
 func (l *DList[T]) ForEachIf(cb func(val T) bool) {
 	for n := l.head.next; n != &l.head; n = n.next {
 		if !cb(n.value) {
diff --git a/queue.go b/queue.go
index a6b3d10..3219367 100644
--- a/queue.go
+++ b/queue.go
@@ -16,34 +16,42 @@ func NewQueue[T any]() *Queue[T] {
 	return &q
 }
 
+// Len implements the Container interface.
 func (q *Queue[T]) Len() int {
 	return q.list.Len()
 }
 
+// IsEmpty implements the Container interface.
 func (q *Queue[T]) IsEmpty() bool {
 	return q.list.IsEmpty()
 }
 
+// Clear implements the Container interface.
 func (q *Queue[T]) Clear() {
 	q.list.Clear()
 }
 
+// Len implements the fmt.Stringer interface.
 func (q *Queue[T]) String() string {
 	return fmt.Sprintf("Queue[%v]", nameOfType[T]())
 }
 
+// PushFront pushed an element to the front of the queue.
 func (q *Queue[T]) PushFront(val T) {
 	q.list.PushFront(val)
 }
 
+// PushBack pushed an element to the back of the queue.
 func (q *Queue[T]) PushBack(val T) {
 	q.list.PushBack(val)
 }
 
+// PopFront popups an element from the front of the queue.
 func (q *Queue[T]) PopFront() (T, bool) {
 	return q.list.PopFront()
 }
 
+// PopBack popups an element from the back of the queue.
 func (q *Queue[T]) PopBack() (T, bool) {
 	return q.list.PopBack()
 }
diff --git a/skiplist.go b/skiplist.go
index d22b6e3..eb85c1d 100644
--- a/skiplist.go
+++ b/skiplist.go
@@ -26,27 +26,20 @@ const (
 //
 // See https://en.wikipedia.org/wiki/Skip_list for more details.
 type SkipList[K any, V any] struct {
-	level int // Current level, may increase dynamically during insertion
-	len   int // Total elements numner in the skiplist.
-	head  skipListNode[K, V]
+	level int                // Current level, may increase dynamically during insertion
+	len   int                // Total elements numner in the skiplist.
+	head  skipListNode[K, V] // head.next[level] is the head of each level.
 	// This cache is used to save the previous nodes when modifying the skip list to avoid
 	// allocating memory each time it is called.
-	prevsCache []*skipListNode[K, V] // Cache to avoid memory allocation.
+	prevsCache []*skipListNode[K, V]
 	rander     *rand.Rand
 	impl       skipListImpl[K, V]
 }
 
 // NewSkipList creates a new SkipList for Ordered key type.
 func NewSkipList[K Ordered, V any]() *SkipList[K, V] {
-	sl := skipListOrdered[K, V]{
-		SkipList: SkipList[K, V]{
-			level: 1,
-			// #nosec G404 -- This is not a security condition
-			rander:     rand.New(rand.NewSource(time.Now().Unix())),
-			prevsCache: make([]*skipListNode[K, V], skipListMaxLevel),
-		},
-	}
-	sl.head.next = make([]*skipListNode[K, V], skipListMaxLevel)
+	sl := skipListOrdered[K, V]{}
+	sl.init()
 	sl.impl = (skipListImpl[K, V])(&sl)
 	return &sl.SkipList
 }
@@ -69,14 +62,17 @@ func NewSkipListFunc[K any, V any](keyCmp CompareFn[K]) *SkipList[K, V] {
 	return &sl.SkipList
 }
 
+// IsEmpty implements the Container interface.
 func (sl *SkipList[K, V]) IsEmpty() bool {
 	return sl.len == 0
 }
 
+// Len implements the Container interface.
 func (sl *SkipList[K, V]) Len() int {
 	return sl.len
 }
 
+// Clear implements the Container interface.
 func (sl *SkipList[K, V]) Clear() {
 	for i := range sl.head.next {
 		sl.head.next[i] = nil
@@ -85,6 +81,7 @@ func (sl *SkipList[K, V]) Clear() {
 	sl.len = 0
 }
 
+// Iterate return an iterator to the skiplist.
 func (sl *SkipList[K, V]) Iterate() MapIterator[K, V] {
 	return &skipListIterator[K, V]{sl.head.next[0], nil}
 }
@@ -128,14 +125,21 @@ func (sl *SkipList[K, V]) Find(key K) *V {
 	return nil
 }
 
+// Has implement the Map interface.
 func (sl *SkipList[K, V]) Has(key K) bool {
 	return sl.impl.findNode(key) != nil
 }
 
+// LowerBound returns an iterator to the first element in the skiplist that
+// does not satisfy element < value (i.e. greater or equal to),
+// or a end itetator if no such element is found.
 func (sl *SkipList[K, V]) LowerBound(key K) MapIterator[K, V] {
 	return &skipListIterator[K, V]{sl.impl.lowerBound(key), nil}
 }
 
+// UpperBound returns an iterator to the first element in the skiplist that
+// does not satisfy value < element (i.e. strictly greater),
+// or a end itetator if no such element is found.
 func (sl *SkipList[K, V]) UpperBound(key K) MapIterator[K, V] {
 	return &skipListIterator[K, V]{sl.impl.upperBound(key), nil}
 }
@@ -162,18 +166,21 @@ func (sl *SkipList[K, V]) Remove(key K) bool {
 	return true
 }
 
+// ForEach implements the Map interface.
 func (sl *SkipList[K, V]) ForEach(op func(K, V)) {
 	for e := sl.head.next[0]; e != nil; e = e.next[0] {
 		op(e.key, e.value)
 	}
 }
 
+// ForEachMutable implements the Map interface.
 func (sl *SkipList[K, V]) ForEachMutable(op func(K, *V)) {
 	for e := sl.head.next[0]; e != nil; e = e.next[0] {
 		op(e.key, &e.value)
 	}
 }
 
+// ForEachIf implements the Map interface.
 func (sl *SkipList[K, V]) ForEachIf(op func(K, V) bool) {
 	for e := sl.head.next[0]; e != nil; e = e.next[0] {
 		if !op(e.key, e.value) {
@@ -182,6 +189,7 @@ func (sl *SkipList[K, V]) ForEachIf(op func(K, V) bool) {
 	}
 }
 
+// ForEachMutableIf implements the Map interface.
 func (sl *SkipList[K, V]) ForEachMutableIf(op func(K, *V) bool) {
 	for e := sl.head.next[0]; e != nil; e = e.next[0] {
 		if !op(e.key, &e.value) {
diff --git a/skiplist_test.go b/skiplist_test.go
index 93ad0ee..489d890 100644
--- a/skiplist_test.go
+++ b/skiplist_test.go
@@ -105,7 +105,7 @@ func TestNewSkipList_Iterate(t *testing.T) {
 	}
 }
 
-func testNewSkipList_Iterater(t *testing.T, sl *SkipList[int, int]) {
+func testNewSkipListIterater(t *testing.T, sl *SkipList[int, int]) {
 	t.Run("LowerBound", func(t *testing.T) {
 		expectEq(t, sl.LowerBound(1).Key(), 1)
 		expectEq(t, sl.LowerBound(3).Key(), 4)
@@ -131,7 +131,7 @@ func testNewSkipList_Iterater(t *testing.T, sl *SkipList[int, int]) {
 
 func TestNewSkipList_Iterater(t *testing.T) {
 	sl := NewSkipListFromMap(map[int]int{1: 1, 2: 2, 4: 4})
-	testNewSkipList_Iterater(t, sl)
+	testNewSkipListIterater(t, sl)
 }
 
 func TestNewSkipList_Func_Iterater(t *testing.T) {
@@ -140,7 +140,7 @@ func TestNewSkipList_Func_Iterater(t *testing.T) {
 	for k, v := range m {
 		sl.Insert(k, v)
 	}
-	testNewSkipList_Iterater(t, sl)
+	testNewSkipListIterater(t, sl)
 }
 func TestSkipList_Insert(t *testing.T) {
 	sl := NewSkipList[int, int]()
diff --git a/stack.go b/stack.go
index 0f369fb..05150ae 100644
--- a/stack.go
+++ b/stack.go
@@ -16,26 +16,32 @@ func NewStackCap[T any](capicity int) *Stack[T] {
 	return &Stack[T]{make([]T, 0, capicity)}
 }
 
+// IsEmpty implements the Container interface.
 func (s *Stack[T]) IsEmpty() bool {
 	return len(s.ele) == 0
 }
 
+// Len implements the Container interface.
 func (s *Stack[T]) Len() int {
 	return len(s.ele)
 }
 
+// Cap returns the capacity of the stack.
 func (s *Stack[T]) Cap() int {
 	return cap(s.ele)
 }
 
+// Clear implements the Container interface.
 func (s *Stack[T]) Clear() {
 	s.ele = s.ele[0:0]
 }
 
+// Push pushes the element to the top of the stack.
 func (s *Stack[T]) Push(t T) {
 	s.ele = append(s.ele, t)
 }
 
+// Pop try popup an element from the top of the stack.
 func (s *Stack[T]) Pop() (val T, ok bool) {
 	var t T
 	if len(s.ele) == 0 {
@@ -46,6 +52,9 @@ func (s *Stack[T]) Pop() (val T, ok bool) {
 	return t, true
 }
 
+// MustPop popups an element from the top of the stack.
+// It must be called whtn IsEmpty() returned false,
+// otherwise it will panic.
 func (s *Stack[T]) MustPop() T {
 	t := s.ele[len(s.ele)-1]
 	s.ele = s.ele[:len(s.ele)-1]
diff --git a/vector.go b/vector.go
index 0c17217..b9d1ecf 100644
--- a/vector.go
+++ b/vector.go
@@ -19,14 +19,17 @@ func MakeVectorOf[T any](v ...T) Vector[T] {
 	return (Vector[T])(v)
 }
 
+// IsEmpty implements the Container interface.
 func (v *Vector[T]) IsEmpty() bool {
 	return len(*v) == 0
 }
 
+// Len implements the Container interface.
 func (v *Vector[T]) Len() int {
 	return len(*v)
 }
 
+// Cap returns the capacity of the vector.
 func (v *Vector[T]) Cap() int {
 	return cap(*v)
 }
@@ -58,14 +61,19 @@ func (v *Vector[T]) Shrink() {
 	}
 }
 
+// At returns the element value at the index i.
+// You can also use the [] operator, and it's better.
 func (v *Vector[T]) At(i int) T {
 	return (*v)[i]
 }
 
+// Set sets the value of the element at the index i.
+// You can also use the [] operator, and it's better.
 func (v *Vector[T]) Set(i int, x T) {
 	(*v)[i] = x
 }
 
+// PushBack pushs an element to the end of the vector.
 func (v *Vector[T]) PushBack(x T) {
 	*v = append(*v, x)
 }
@@ -104,12 +112,12 @@ func (v *Vector[T]) Remove(i int) {
 	v.RemoveRange(i, i+1)
 }
 
-// Remove removes the elements in the range[i, j) from the vector.
+// RemoveRange removes the elements in the range[i, j) from the vector.
 func (v *Vector[T]) RemoveRange(i, j int) {
 	*v = append((*v)[:i], (*v)[j:]...)
 }
 
-// Remove removes the elements in the range[i, i+len) from the vector.
+// RemoveLength removes the elements in the range[i, i+len) from the vector.
 func (v *Vector[T]) RemoveLength(i int, len int) {
 	v.RemoveRange(i, i+len)
 }