It's easy to show beautiful examples that may actually depend on other
things. Whether that's representative of all contracts is another
I agree. There are also many contracts which are simply too hard to write down formally. But many are also easily captured in formal manner in my experience. The question is, of course, how many and you make a fair point there.
@Chris and others requesting data: my time is way too limited to provide a large-scale code analysis of many pypi packages (family obligations with a toddler, 9-6 job). I'm not doing research, and such a study would require substantial time resources. Is there an alternative request that you think that I (and other volunteers?) could accomplish in a reasonable (free) time? Maybe you could compile a list of 100-200 (or even less) functions from representative modules and I try to annotate them with contracts and we see if that's convincing? It's up to you to pick representative functions and up to me to annotate them with contracts. That would diffuse the argument that I intentionally picked the functions whose contracts are easily and nice to annotate.