Yes I agree, if I was writing this for my own project I'm pretty sure I would do what you have done and use classes with an `area` method. (FWIW I think the dataclass approach is nicer for this example than namespacing separate `area` functions using modules)

You could define it as a typing.Protocol too.

My point was just that, even if for some reason you prefer function overloading, the restrictions needed to fit within the constraints of functool.singledispatch arguably lead to cleaner code than the complicated mess in the OP article.

This would look messy if you implemented as just a single function with variable no of kwargs that you sniffed in the body, and I don't think applying function overloading alone as OP has done solves the underlying problem.