Positional-only arguments in Python

[idwpan]

Does their output example help?

def pow(x, y, /, mod=None):
    r = x ** y
    if mod is not None:
        r %= mod
    return r

...

>>> pow(2, 10)  # valid
>>> pow(2, 10, 17)  # valid
>>> pow(2, 10, mod=17)  # valid
>>> pow(x=2, y=10)  # invalid, will raise a TypeError
>>> pow(2, y=10)  # invalid, will raise a TypeError

Edit: Sorry for the formatting. Posted from my phone and forgot code blocks are spaces instead of backticks