def test_flatten(self):
bj = Blackjack()
lst1 = []
lst3 = [[1,2,3],[1,'hello',4]]
lst4 = [[1,2,3],[1,2,4],[8,9,10]]
self.assertEqual(bj.flatten(lst1),[])
self.assertEqual(bj.flatten(lst3),[1,2,3,1,'hello',4])
self.assertEqual(bj.flatten(lst4),[1,2,3,1,2,4,8,9,10])
def test_flatten(self):
bj = Blackjack()
lst1 = []
lst3 = [[1, 2, 3], [1, 'hello', 4]]
lst4 = [[1, 2, 3], [1, 2, 4], [8, 9, 10]]
self.assertEqual(bj.flatten(lst1), [])
self.assertEqual(bj.flatten(lst3), [1, 2, 3, 1, 'hello', 4])
self.assertEqual(bj.flatten(lst4), [1, 2, 3, 1, 2, 4, 8, 9, 10])
