'Closeness centrality: star'

def test_star(self):

    G = nx.Graph()
    nx.add_star(G, ['a', 'b', 'c', 'd'])
    b = nx.current_flow_closeness_centrality(G)
    b_answer = {'a': (1.0 / 3), 'b': (0.6 / 3), 'c': (0.6 / 3), 'd': (0.6 / 3)}
    for n in sorted(G):
        assert_almost_equal(b[n], b_answer[n])
