[$] Positional-only parameters for Python

Arguments can be passed to Python functions by position or by
keyword—generally both. There are times when API designers may wish to
restrict some function parameters to only be passed by position, which is
harder than some think it should be in pure Python. That has led to a PEP
that is meant to make the situation better, but
opponents say it doesn't really do that;
it simply replaces one obscure mechanism with another. The PEP was
assigned a fairly well-known 'BDFL delegate' (former BDFL Guido van Rossum), who has
accepted it, presumably for Python 3.8.