def test_vary_delete(self):
test = Chain({(1,): {1: 1}})
test.vary_weight((1,), 1, -1)
check = Chain({})
self.assertEqual(test, check)
def test_vary3(self):
test = Chain({(1,): {1: 1}})
test.vary_weight((1,), 2)
check = Chain({(1,): {1: 1, 2: 1}})
self.assertEqual(test, check)