def METHOD_NAME(f):
    ns = dict(n=12, pi=math.pi, stuff='hello there', os=os)
    s = f.format(" {stuff.split()[:]} ", **ns)
    assert s == " ['hello', 'there'] "
    s = f.format(" {stuff.split()[::-1]} ", **ns)
    assert s == " ['there', 'hello'] "
    s = f.format("{stuff[::2]}", **ns)
    assert s == ns["stuff"][::2]
    pytest.raises(SyntaxError, f.format, "{n:x}", **ns)