def test_maxNum_5():
    assert maxNum([4, 4, "4", 3]) == None
def test_maxNum_4():
    assert maxNum("1,2,3") == None
def test_maxNum_2():
    assert maxNum([4, 3, 12, 2]) == 12
def test_maxNum_3():
    assert maxNum([-1.1, -1.2, -3.3, -2.2]) == -1.1
def test_maxNum_1():
    assert maxNum([]) == None