如何为自定义双向链表实现实现迭代器？

class Node:
    def __init__(self, value):
        self.value = value
        self.next = None
        self.previous = None

class DoublyLinkedList:
    def __init__(self):
        self.head = None
        self.tail = None

    def insert(self, value):
        new_node = Node(value)
        if self.head is None:
            self.head = new_node
            self.tail = new_node
        else:
            new_node.previous = self.tail
            self.tail.next = new_node
            self.tail = new_node

    def remove(self, value):
        current = self.head
        while current is not None:
            if current.value == value:
                if current.previous is not None:
                    current.previous.next = current.next
                else:
                    self.head = current.next
                if current.next is not None:
                    current.next.previous = current.previous
                else:
                    self.tail = current.previous
                return
            current = current.next

    def getIterator(self):
        return DoublyLinkedListIterator(self.head)

class DoublyLinkedListIterator:
    def __init__(self, head):
        self.current = head

    def hasNext(self):
        return self.current is not None

    def next(self):
        if self.hasNext():
            value = self.current.value
            self.current = self.current.next
            return value

    def hasPrevious(self):
        return self.current.previous is not None

    def previous(self):
        if self.hasPrevious():
            value = self.current.previous.value
            self.current = self.current.previous
            return value