def test_indexOf_5(): assert indexOf(1, "1") == None
def test_indexOf_4(): assert indexOf(1, [3, 1, 1, 2]) == 1
def test_indexOf_2(): assert indexOf(3, ["1", "2", "3"]) == None
def test_indexOf_3(): assert indexOf(3, []) == None
def test_indexOf_1(): assert indexOf("tree", [4, "x", "tree", -1.2]) == 2