如何在Networkx中使用节点标签搜索特定路径并返回节点in？

import networkx as nx

# 创建一个有向图
G = nx.DiGraph()

# 添加节点
G.add_node(1, label='A')
G.add_node(2, label='B')
G.add_node(3, label='C')
G.add_node(4, label='D')

# 添加边
G.add_edge(1, 2)
G.add_edge(2, 3)
G.add_edge(3, 4)

# 定义一个函数来搜索特定路径并返回节点in
def search_path(graph, start_node, target_label, path=[]):
    # 将当前节点添加到路径中
    path = path + [start_node]

    # 如果当前节点的标签与目标标签匹配，则返回路径
    if graph.nodes[start_node]['label'] == target_label:
        return path

    # 遍历当前节点的邻居节点
    for neighbor in graph.neighbors(start_node):
        # 如果邻居节点不在路径中，则递归调用搜索函数
        if neighbor not in path:
            new_path = search_path(graph, neighbor, target_label, path)
            # 如果找到路径，则返回路径
            if new_path is not None:
                return new_path

    # 如果没有找到路径，则返回None
    return None

# 搜索特定路径并返回节点in
target_label = 'D'
start_node = 1
path = search_path(G, start_node, target_label)

if path is not None:
    # 输出路径中的节点in
    for node in path:
        print(node)
else:
    print("未找到路径")