Comment by mjr00

> But by it's nature, duck typing supports an unbounded number of input types and is what Python was built on.

You're trying to shove a square peg into a round hole. It's not about right or wrong. Either you want your function to operate on any type, attempt to add the two values (or perform any operation which may or may not be supported, i.e. duck typing), and throw an runtime error if it doesn't work--in which case you can leave it untyped or use `Any`--or you want stronger type safety guarantees so you can validate before runtime that nobody is calling your method with incorrect arguments, in which case you have to represent the types which you accept somehow.

If you want to have a method that's fully duck typed, you're supposed to use `Any`. That's exactly why it exists. Inventing contrived scenarios about how you can't use `Any` is missing the point. It's like complaining C doesn't work if you're not allowed to use pointers.

You're right that historically Python code was written with duck typing in mind, but now even highly flexible libraries like Pandas have type definition support. The ecosystem is way different from even 5-6 years ago, I can't think of any well-known libraries which don't have good typing support by now.