It looks to me like all the information is already there. I don't really see a point in making the docs less readable by highlighting the least important information.

I don't really see a point in making the docs less readable by highlighting the least important information.

I agree that it's not relevant for many use cases, but it's a gotcha if it is. It definitely was a gotcha for me, Cython had this feature missing for quite a while, until someone noticed that it didn't work there (that was years ago). So – it's clearly not often needed, but that also means that it's very unlikely to be tested for and very likely to go unnoticed. And apparently, others have noticed the difference, too, and written up ticket capi-workgroup/problems#6.

OTOH, you could argue that the function name is such an obvious equivalent to set.__contains__ that people won't bother looking it up in the documentation at all, and, thus, won't notice the sentence either way, however visible it is in the docs…

Thanks for the suggestion, but I'm going to decline. I don't buy that of the three sentences in the docs, that this one needs to be moved into a large box. It reads plainly enough and it covers a really minor, mostly unused feature.