def test_disordered():
assert find_target(disordered_list, 0) is 6
def test_all_equals():
assert find_target([4] * 100, 4) is 0
def test_many_missing():
assert find_target(ordered_list, 0) is None
def test_many():
assert find_target(ordered_list, 2) is 2
assert find_target(ordered_list, -1) is 1
def test_single_missing():
assert find_target([1], 2) is None
def test_single():
assert find_target([1], 1) is 0
assert find_target([None], None) is 0
def test_empty():
assert find_target([], 1) is None