def test_degree(self):
G = Graph({
'V': ['a', 'd', 'b', 'c', 'e', 'f'],
'E': [('a', 'd'), ('b', 'c'), ('c', 'c'), ('c', 'e'), ('d', 'c')]
})
self.assertEqual(G.degree('a'), 1)
self.assertEqual(G.degree('c'), 5)
self.assertEqual(G.degree('d'), 2)
self.assertEqual(G.degree('f'), 0)
