def test_neighbors(self):
g = Graph(range(5))
edges = [(0, 1), (0, 3), (0, 4), (1, 2), (2, 3), (2, 4)]
g.add_edges(edges)
self.assertEqual([1, 3, 4], g.neighbors(0))
self.assertEqual([1, 3, 4], g.neighbors(2))
