如何使用python统计LinkedList的节点数

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

def count_nodes(head):
    count = 0
    current = head
    while current:
        count += 1
        current = current.next
    return count

# 创建一个链表
node1 = ListNode(1)
node2 = ListNode(2)
node3 = ListNode(3)
node4 = ListNode(4)

node1.next = node2
node2.next = node3
node3.next = node4

# 统计链表节点数
node_count = count_nodes(node1)
print("链表的节点数为:", node_count)