如何获得图中给定节点的所有后继节点？

# 图的邻接表表示
graph = {
    'A': ['B', 'C'],
    'B': ['D', 'E'],
    'C': ['F'],
    'D': [],
    'E': ['F'],
    'F': []
}

# DFS遍历函数
def dfs(graph, start, visited, successors):
    visited.add(start)
    for neighbor in graph[start]:
        if neighbor not in visited:
            successors.add(neighbor)
            dfs(graph, neighbor, visited, successors)

# 获取给定节点的所有后继节点
def get_successors(graph, node):
    visited = set()
    successors = set()
    dfs(graph, node, visited, successors)
    return successors

# 示例用法
successors = get_successors(graph, 'A')
print(successors)