如何在双向链表的第一个节点之前插入新节点？

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

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

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

# 使用示例
dll = DoublyLinkedList()
dll.insert_at_beginning(3)
dll.insert_at_beginning(2)
dll.insert_at_beginning(1)