Add syntax for late-bound function defaults

[evhub]

See: https://www.python.org/dev/peps/pep-0671/

Would need to be supported in normal and pattern-matching function definition.

[evhub]

Currently, pattern-matching functions always use late-bound defaults, which is a bug right now, but could be turned into a feature to help support this.

[Jatinjain07Dazai]

I would love to work on it can you assign development of this feature to me

[evhub]

This is now a full-fledged feature of pattern-matching functions, including support for syntax such as match def f(x, y=x) = (x, y).