如何将顶点连接(有路径)到3个顶点

class Graph:
    def __init__(self):
        self.vertices = {}

    def add_vertex(self, vertex):
        self.vertices[vertex] = []

    def add_edge(self, vertex1, vertex2):
        self.vertices[vertex1].append(vertex2)
        self.vertices[vertex2].append(vertex1)

# 创建图对象
graph = Graph()

# 添加三个顶点
graph.add_vertex("A")
graph.add_vertex("B")
graph.add_vertex("C")

# 连接顶点到三个顶点
graph.add_edge("A", "B")
graph.add_edge("A", "C")
graph.add_edge("B", "C")