what is ,*, ?

[dvs1]

def test(a, b='test'):
    print(a)
    print(b)

def test2(a, *, b='test'):
    print(a)
    print(b)
    
test('hello', 'world')
test2('hello', b='world')

If you write: test2('hello', 'world')
you get: TypeError: test2() takes 1 positional argument but 2 were given

https://www.python.org/dev/peps/pep-3102/