def test_simple(simple_string): assert firstlast(simple_string) == 'ad'
def test_element_0(simple_string): assert firstlast(simple_string)[0] == 'a'
def test_first_last_list(): assert firstlast([1, 2, 3, 4]) == [1, 4]
def test_first_last_string(): assert firstlast("abcd") == "ad"
def test_first_last_tuple(): assert firstlast((1, 2, 3, 4)) == (1, 4)