def test_equals_2(self): self.assertEqual(find_missing_number('1 3'), 2)
def test_equals_5(self): self.assertEqual(find_missing_number('1 2 3'), 0)
def test_equals(self): self.assertEqual(find_missing_number('1 2 3 5'), 4)
def test_equals_4(self): self.assertEqual(find_missing_number('a b c'), 1)