'Betweenness centrality: star'

def test_star(self):

    G = nx.Graph()
    nx.add_star(G, ['a', 'b', 'c', 'd'])
    b = nx.current_flow_betweenness_centrality(G, normalized=True)
    b_answer = {'a': 1.0, 'b': 0.0, 'c': 0.0, 'd': 0.0}
    for n in sorted(G):
        assert_almost_equal(b[n], b_answer[n])
