There was a presentation pycon 2021 describing how protocols enables better typing in several cases: https://m.youtube.com/watch?v=kDDCKwP7QgQ&list=PL2Uw4_HvXqv

There was a presentation pycon 2021 describing how protocols enables better typing in several cases: https://m.youtube.com/watch?v=kDDCKwP7QgQ&list=PL2Uw4_HvXqvYk1Y5P8kryoyd83L_0Uk5K&index=42 https://m.youtube.com/watch?v=kDDCKwP7QgQ&list=PL2Uw4_HvXqvY.... They sound similar to what you describe in that the protocol allows you to describe the features of the thing you need and the type checker can then help you determine that the thing you need has those features. Doing this kind of feature detection allows you to check ahead of time whether a call is likely to succeed but especially for a language like python you still need runtime guards of some kind to limit the impact of unexpected cases.