def test_copy_after_map(self):
a = Chain(range(3)).map(lambda x: 2 * x)
b = a.copy()
a.map(lambda x: 3 * x)
self.assertEqual(list(a), [0, 6, 12])
self.assertEqual(list(b), [0, 2, 4])
def test_copy(self):
a = Chain(range(3))
b = a.copy()
a.map(lambda x: 2 * x)
self.assertEqual(list(a), [0, 2, 4])
self.assertEqual(list(b), [0, 1, 2])