def test_find_duplicate(self):
self.assertEqual(find_duplicate([1, 3, 4, 2, 2]), 2)
self.assertEqual(find_duplicate([3, 1, 3, 4, 2]), 3)
self.assertEqual(find_duplicate([10, 7, 5, 8, 11, 9, 11]), 11)
self.assertEqual(find_duplicate([100, 90, 80, 50, 20, 10, 101, 100]),
100)
self.assertEqual(
find_duplicate([1050, 270, 1540, 3800, 2, 3000, 1540]), 1540)
self.assertEqual(
find_duplicate([
100, 55, 4, 98, 10, 18, 90, 95, 43, 11, 47, 67, 89, 42, 49, 79,
100
]), 100)
def test1(self):
stimulus = [3, 2, 1]
self.assertEqual([], find_duplicate(stimulus))
def test2(self):
stimulus = [2, 1, 3, 1]
self.assertEqual([1], find_duplicate(stimulus))
